[Qemu-devel] [PATCH] add QEMU_LD_PREFIX environment variable

[Qemu-devel] [PATCH] add QEMU_LD_PREFIX environment variable

[josch]

From: Johannes Schauer <j.schauer@email.de>

Hi,

qemu allows to specify the elf interpreter prefix with the -L option. When
using qemu user mode emulation through the binfmt mechanism, it is not
possible to pass any commandline arguments to qemu. Having qemu evaluate an
environment variable makes it possible to still supply a custom elf
interpreter prefix, even if qemu is executed by the binfmt mechanism.

My motivation is an emdebian project which creates foreign debian
bootstraps. Since foreign binaries are executed without an explicit
qemu-user call but by the binfmt mechanism, it relied on having appropriate
content in /etc/qemu-binfmt/$arch/ which is the default elf interpreter
prefix path on debian. The downside currently is, that the shared libraries
in /etc/qemu-binfmt/$arch/ have to be adapted very often for different
debian systems running on the same qemu $arch. This could be avoided by
setting the proposed environment variable QEMU_LD_PREFIX to the just
created debian rootfs. As mentioned earlier, the usage of the -L option
is not possible in this scenario because qemu-user is only implicitly
called by the binfmt mechanism.

Hopefully this change can be applied.

thanks!

cheers, josch

Johannes Schauer (1):
  add QEMU_LD_PREFIX environment variable

 linux-user/main.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

-- 
1.7.5.4

[Qemu-devel] [PATCH] add QEMU_LD_PREFIX environment variable

[josch]

From: Johannes Schauer <j.schauer@email.de>


Signed-off-by: Johannes Schauer <j.schauer@email.de>
---
 linux-user/main.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/linux-user/main.c b/linux-user/main.c
index 289054b..b590aa7 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -2891,6 +2891,11 @@ int main(int argc, char **argv, char **envp)
     cpudef_setup(); /* parse cpu definitions in target config file (TBD) */
 #endif
 
+    /* read interp_prefix from environment variable */
+    if (getenv("QEMU_LD_PREFIX") != NULL) {
+        interp_prefix = getenv("QEMU_LD_PREFIX");
+    }
+
     optind = 1;
     for(;;) {
         if (optind >= argc)
-- 
1.7.5.4

Re: [Qemu-devel] [PATCH] add QEMU_LD_PREFIX environment variable

[Riku Voipio]

On Sat, Jul 23, 2011 at 07:47:49AM +0200, josch wrote:
> This could be avoided by setting the proposed environment variable 
> QEMU_LD_PREFIX to the just
> created debian rootfs. As mentioned earlier, the usage of the -L option
> is not possible in this scenario because qemu-user is only implicitly
> called by the binfmt mechanism.

What worries me here is that we are beginning to add a enviroment variable
for each and every command line option of qemu linux-user. I think it would
be better to have a wrapper binary to be registered as the binfmt runner.
Alternatively we should have a generic setup for mapping enviroment variables
to command line options. Now we get special per-option code every time someone 
needs to setup a command line option from binfmt.

Riku

Re: [Qemu-devel] [PATCH] add QEMU_LD_PREFIX environment variable

[Johannes Schauer]

Hi,

On Thu, Jul 28, 2011 at 11:41:09AM +0300, Riku Voipio wrote:
> On Sat, Jul 23, 2011 at 07:47:49AM +0200, josch wrote:
> > This could be avoided by setting the proposed environment variable 
> > QEMU_LD_PREFIX to the just
> > created debian rootfs. As mentioned earlier, the usage of the -L option
> > is not possible in this scenario because qemu-user is only implicitly
> > called by the binfmt mechanism.
> 
> What worries me here is that we are beginning to add a enviroment
> variable for each and every command line option of qemu linux-user.

Are there other environment variables? I didnt see any? (well besides
QEMU_STRACE that is)

> I think it would be better to have a wrapper binary to be registered
> as the binfmt runner.

If you need help with writing something - dont hesitate to ask for help.
I'm very interested in having this functionality working because of the
reasons I gave in my initial mail. [1]

> Alternatively we should have a generic setup for mapping enviroment
> variables to command line options. Now we get special per-option code
> every time someone needs to setup a command line option from binfmt.

What other options are there that would be interesting for binfmt?

I was also sending this patch to qemu-devel list a month ago but got no
reply. [2]

As I said - if you would like a wrapper or a generic setup for mapping
env variables to commandline parameters and dont have time to do it
yourself, dont hesitate to delegate some work to me :)


@Geert Stappers:

you are patching bsd-user/main.c and darwin-user/main.c as well. I take
it that you did test your changes on those platforms? does it work there
as well? I have no clue of darwin but is it really useful there?

cheers, josch

[1] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=632192#5
[2] http://lists.nongnu.org/archive/html/qemu-devel/2011-07/msg00459.html

Re: [Qemu-devel] [PATCH] add QEMU_LD_PREFIX environment variable

[Geert Stappers]

On Thu, Jul 28, 2011 at 01:24:47PM +0200, Johannes Schauer wrote:
> 
> @Geert Stappers:
> 
> you are patching bsd-user/main.c and darwin-user/main.c as well. I take
> it that you did test your changes on those platforms? does it work there
> as well? I have no clue of darwin but is it really useful there?

They only check I did,
was checking if BSD and Darwing have getenv(), they do.

I consider the 
+    /* read interp_prefix from environment variable */
+    if (getenv("QEMU_LD_PREFIX") != NULL) {
+        interp_prefix = getenv("QEMU_LD_PREFIX");
to Darwin and BSD as harmless. In fact only reason for those additional
lines were to bring attention to those operating systems.

With the idea^Whope of better acception from upstream.


Cheers
Geert Stappers

Re: [Qemu-devel] [PATCH] add QEMU_LD_PREFIX environment variable

[Alexander Graf]

On 28.07.2011, at 18:50, Geert Stappers wrote:

> On Thu, Jul 28, 2011 at 01:24:47PM +0200, Johannes Schauer wrote:
>> 
>> @Geert Stappers:
>> 
>> you are patching bsd-user/main.c and darwin-user/main.c as well. I take
>> it that you did test your changes on those platforms? does it work there
>> as well? I have no clue of darwin but is it really useful there?
> 
> They only check I did,
> was checking if BSD and Darwing have getenv(), they do.
> 
> I consider the 
> +    /* read interp_prefix from environment variable */
> +    if (getenv("QEMU_LD_PREFIX") != NULL) {
> +        interp_prefix = getenv("QEMU_LD_PREFIX");
> to Darwin and BSD as harmless. In fact only reason for those additional
> lines were to bring attention to those operating systems.

It's called DYLD_PRELOAD on Darwin :). However, I do think that if anything this should be an alias, so you can set either of the two. If anyone cares about darwin-user at all.


Alex

Re: [Qemu-devel] Bug#632192: [PATCH] add QEMU_LD_PREFIX environment variable

[Vagrant Cascadian]

On Thu, Jul 28, 2011 at 11:41:09AM +0300, Riku Voipio wrote:
> On Sat, Jul 23, 2011 at 07:47:49AM +0200, josch wrote:
> > This could be avoided by setting the proposed environment variable 
> > QEMU_LD_PREFIX to the just
> > created debian rootfs. As mentioned earlier, the usage of the -L option
> > is not possible in this scenario because qemu-user is only implicitly
> > called by the binfmt mechanism.
> 
> What worries me here is that we are beginning to add a enviroment variable
> for each and every command line option of qemu linux-user. I think it would
> be better to have a wrapper binary to be registered as the binfmt runner.

setting up a wrapper makes trivial cross-architecture chroots harder as you'll 
have to copy two binaries into the chroot, and i'm not sure if it would work at 
all, as the wrapper will need to somehow emulate it's own interpreter...


> Alternatively we should have a generic setup for mapping enviroment variables
> to command line options. Now we get special per-option code every time someone 
> needs to setup a command line option from binfmt.

this would seem a bit better alternative to me...


live well,
  vagrant

Re: [Qemu-devel] Bug#632192: [PATCH] add QEMU_LD_PREFIX environment variable

[Johannes Schauer]

On Fri, Jul 29, 2011 at 05:52:50AM -0700, Vagrant Cascadian wrote:
> setting up a wrapper makes trivial cross-architecture chroots harder
> as you'll have to copy two binaries into the chroot, and i'm not sure
> if it would work at all, as the wrapper will need to somehow emulate
> it's own interpreter...

Agreed - this makes a wrapper not an option. I didnt think of that.

> > Alternatively we should have a generic setup for mapping enviroment
> > variables to command line options. Now we get special per-option
> > code every time someone needs to setup a command line option from
> > binfmt.
> 
> this would seem a bit better alternative to me...

So if we agree on using environment variables to pass options to
qemu-user we next need to agree on how to name the options.

The following commandline arguments exist (in order as they are checked
in linux-user/main.c) and I shortly described and proposed a name for
the environment variable in the same line.

-d (activate log)             - QEMU_LOG
-D (logfile)                  - QEMU_LOGFILE
-E (set target env variabe)   - QEMU_SET_ENV
-U (unset target env variabe) - QEMU_UNSET_ENV
-0 (set target argv[0])       - QEMU_ARGV0
-s (stack size)               - QEMU_STACK_SIZE
-L (elf interpreter prefix)   - QEMU_LD_PREFIX
-p (page size)                - QEMU_PAGESIZE
-g (listen for gdb on port)   - QEMU_GDB
-r (uname)                    - QEMU_UNAME
-cpu (cpu model)              - QEMU_CPU
-B (guest base)               - QEMU_GUEST_BASE
-R (reserved virtual address) - QEMU_RESERVED_VA
-drop-ld-preload              - QEMU_DROP_LD_PRELOAD
-singlestep                   - QEMU_SINGLESTEP
-strace                       - QEMU_STRACE

also, there already is the QEMU_STRACE environment variable which could
be incorporated into the solution?

the -E and -U options can be specified several times so the environment
variables should be able to receive a list - maybe in the getsubopt(3)
style?

So what do you think?

cheers, josch

Re: [Qemu-devel] Bug#632192: [PATCH] add QEMU_LD_PREFIX environment variable

[Riku Voipio]

On Fri, Jul 29, 2011 at 05:21:59PM +0200, Johannes Schauer wrote:
> So if we agree on using environment variables to pass options to
> qemu-user we next need to agree on how to name the options.
 
> The following commandline arguments exist (in order as they are checked
> in linux-user/main.c) and I shortly described and proposed a name for
> the environment variable in the same line.
 
> -d (activate log)             - QEMU_LOG
> -D (logfile)                  - QEMU_LOGFILE
> -E (set target env variabe)   - QEMU_SET_ENV
> -U (unset target env variabe) - QEMU_UNSET_ENV
> -0 (set target argv[0])       - QEMU_ARGV0
> -s (stack size)               - QEMU_STACK_SIZE
> -L (elf interpreter prefix)   - QEMU_LD_PREFIX
> -p (page size)                - QEMU_PAGESIZE
> -g (listen for gdb on port)   - QEMU_GDB
> -r (uname)                    - QEMU_UNAME
> -cpu (cpu model)              - QEMU_CPU
> -B (guest base)               - QEMU_GUEST_BASE
> -R (reserved virtual address) - QEMU_RESERVED_VA
> -drop-ld-preload              - QEMU_DROP_LD_PRELOAD

This is a legacy option that could be removed already. The
-U LD_PRELOAD replaces this option. The only known user of this
option (scratchbox) has migrated -U LD_PRELOAD years ago.

> -singlestep                   - QEMU_SINGLESTEP
> -strace                       - QEMU_STRACE
 
> also, there already is the QEMU_STRACE environment variable which could
> be incorporated into the solution?

Else names look good to me.
 
> the -E and -U options can be specified several times so the environment
> variables should be able to receive a list - maybe in the getsubopt(3)
> style?

getsubopt would mean that passing enviroment variable contents with commas
wouldn't work. Perhaps that would still be an acceptable limitation.

Riku

[Qemu-devel] [PATCH] introduce environment variables for all qemu-user options

[j.schauer]

From: Johannes Schauer <j.schauer@email.de>

A first try to introduce a generic setup for mapping environment variables to
command line options.

I'm afraid to code something for platforms I can't do runtime tests on, so this 
is only for linux-user for now.

Signed-off-by: Johannes Schauer <j.schauer@email.de>
---
 linux-user/main.c |  147 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 144 insertions(+), 3 deletions(-)

diff --git a/linux-user/main.c b/linux-user/main.c
index dbba8be..fb986e3 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -2640,26 +2640,51 @@ static void usage(void)
            "-E var=value      sets/modifies targets environment variable(s)\n"
            "-U var            unsets targets environment variable(s)\n"
            "-0 argv0          forces target process argv[0] to be argv0\n"
+           "-r uname          set qemu uname release string\n"
 #if defined(CONFIG_USE_GUEST_BASE)
            "-B address        set guest_base address to address\n"
            "-R size           reserve size bytes for guest virtual address space\n"
 #endif
            "\n"
+           "Standard environment variables:\n"
+           "QEMU_GDB          see the -g option\n"
+           "QEMU_LD_PREFIX    see the -L option\n"
+           "QEMU_STACK_SIZE   see the -s option\n"
+           "QEMU_CPU          see the -cpu option\n"
+           "QEMU_SET_ENV      see the -E option, comma separated list of arguments\n"
+           "QEMU_UNSET_ENV    see the -U option, comma separated list of arguments\n"
+           "QEMU_ARGV0        see the -0 option\n"
+           "QEMU_UNAME        see the -r option\n"
+#if defined(CONFIG_USE_GUEST_BASE)
+           "QEMU_GUEST_BASE   see the -B option\n"
+           "QEMU_RESERVED_VA  see the -R option\n"
+#endif
+           "\n"
            "Debug options:\n"
            "-d options   activate log (logfile=%s)\n"
            "-p pagesize  set the host page size to 'pagesize'\n"
            "-singlestep  always run in singlestep mode\n"
            "-strace      log system calls\n"
            "\n"
-           "Environment variables:\n"
-           "QEMU_STRACE       Print system calls and arguments similar to the\n"
-           "                  'strace' program.  Enable by setting to any value.\n"
+           "Debug environment variables:\n"
+           "QEMU_LOG          see the -d option\n"
+           "QEMU_PAGESIZE     see the -p option\n"
+           "QEMU_SINGLESTEP   see the -singlestep option\n"
+           "QEMU_STRACE       see the -strace option\n"
+           "\n"
            "You can use -E and -U options to set/unset environment variables\n"
            "for target process.  It is possible to provide several variables\n"
            "by repeating the option.  For example:\n"
            "    -E var1=val2 -E var2=val2 -U LD_PRELOAD -U LD_DEBUG\n"
            "Note that if you provide several changes to single variable\n"
            "last change will stay in effect.\n"
+           "Using the environment variables QEMU_SET_ENV and QEMU_UNSET_ENV\n"
+           "to set/unset environment variables for target process is\n"
+           "possible by a comma separated list of values in getsubopt(3)\n"
+           "style. For example:\n"
+           "    QEMU_SET_ENV=var1=val2,var2=val2 QEMU_UNSET_ENV=LD_PRELOAD,LD_DEBUG\n"
+           "Note that if you provide several changes to single variable\n"
+           "last change will stay in effect.\n"
            ,
            TARGET_ARCH,
            interp_prefix,
@@ -2758,6 +2783,122 @@ int main(int argc, char **argv, char **envp)
     cpudef_setup(); /* parse cpu definitions in target config file (TBD) */
 #endif
 
+    if ((r = getenv("QEMU_LOG")) != NULL) {
+        int mask;
+        const CPULogItem *item;
+        mask = cpu_str_to_log_mask(r);
+        if (!mask) {
+            printf("Log items (comma separated):\n");
+            for(item = cpu_log_items; item->mask != 0; item++) {
+                printf("%-10s %s\n", item->name, item->help);
+            }
+            exit(1);
+        }
+        cpu_set_log(mask);
+    }
+    if ((r = getenv("QEMU_SET_ENV")) != NULL) {
+        char *p, *token;
+        p = strdup(r);
+        while ((token = strsep(&p, ",")) != NULL) {
+            if (envlist_setenv(envlist, token) != 0)
+                usage();
+        }
+        free(p);
+    }
+    if ((r = getenv("QEMU_UNSET_ENV")) != NULL) {
+        char *p, *token;
+        p = strdup(r);
+        while ((token = strsep(&p, ",")) != NULL) {
+            if (envlist_unsetenv(envlist, token) != 0)
+                usage();
+        }
+        free(p);
+    }
+    if ((r = getenv("QEMU_ARGV0")) != NULL) {
+        argv0 = strdup(r);
+    }
+    if ((r = getenv("QEMU_STACK_SIZE")) != NULL) {
+        guest_stack_size = strtoul(r, (char **)&r, 0);
+        if (guest_stack_size == 0)
+            usage();
+        if (*r == 'M')
+            guest_stack_size *= 1024 * 1024;
+        else if (*r == 'k' || *r == 'K')
+            guest_stack_size *= 1024;
+    }
+    if ((r = getenv("QEMU_LD_PREFIX")) != NULL) {
+        interp_prefix = strdup(r);
+    }
+    if ((r = getenv("QEMU_PAGESIZE")) != NULL) {
+        qemu_host_page_size = atoi(r);
+        if (qemu_host_page_size == 0 ||
+            (qemu_host_page_size & (qemu_host_page_size - 1)) != 0) {
+            fprintf(stderr, "page size must be a power of two\n");
+            exit(1);
+        }
+    }
+    if ((r = getenv("QEMU_GDB")) != NULL) {
+        gdbstub_port = atoi(r);
+    }
+    if ((r = getenv("QEMU_UNAME")) != NULL) {
+        qemu_uname_release = strdup(r);
+    }
+    if ((r = getenv("QEMU_CPU")) != NULL) {
+        cpu_model = strdup(r);
+        if (cpu_model == NULL || strcmp(cpu_model, "?") == 0) {
+/* XXX: implement xxx_cpu_list for targets that still miss it */
+#if defined(cpu_list_id)
+            cpu_list_id(stdout, &fprintf, "");
+#elif defined(cpu_list)
+            cpu_list(stdout, &fprintf); /* deprecated */
+#endif
+            exit(1);
+        }
+    }
+#if defined(CONFIG_USE_GUEST_BASE)
+    if ((r = getenv("QEMU_GUEST_BASE")) != NULL) {
+       guest_base = strtol(r, NULL, 0);
+       have_guest_base = 1;
+    }
+    if ((r = getenv("QEMU_QEMU_RESERVED_VA")) != NULL) {
+        char *p;
+        int shift = 0;
+        reserved_va = strtoul(r, &p, 0);
+        switch (*p) {
+        case 'k':
+        case 'K':
+            shift = 10;
+            break;
+        case 'M':
+            shift = 20;
+            break;
+        case 'G':
+            shift = 30;
+            break;
+        }
+        if (shift) {
+            unsigned long unshifted = reserved_va;
+            p++;
+            reserved_va <<= shift;
+            if (((reserved_va >> shift) != unshifted)
+#if HOST_LONG_BITS > TARGET_VIRT_ADDR_SPACE_BITS
+                || (reserved_va > (1ul << TARGET_VIRT_ADDR_SPACE_BITS))
+#endif
+                ) {
+                fprintf(stderr, "Reserved virtual address too big\n");
+                exit(1);
+            }
+        }
+        if (*p) {
+            fprintf(stderr, "Unrecognised -R size suffix '%s'\n", p);
+            exit(1);
+        }
+    }
+#endif
+    if ((r = getenv("QEMU_SINGLESTEP")) != NULL) {
+        singlestep = 1;
+    }
+
     optind = 1;
     for(;;) {
         if (optind >= argc)
-- 
1.7.5.4

Re: [Qemu-devel] [PATCH] introduce environment variables for all qemu-user options

[Peter Maydell]

On 31 July 2011 12:51,  <j.schauer@email.de> wrote:
> +    if ((r = getenv("QEMU_STACK_SIZE")) != NULL) {
> +        guest_stack_size = strtoul(r, (char **)&r, 0);
> +        if (guest_stack_size == 0)
> +            usage();
> +        if (*r == 'M')
> +            guest_stack_size *= 1024 * 1024;
> +        else if (*r == 'k' || *r == 'K')
> +            guest_stack_size *= 1024;
> +    }

[etc]

This is all basically duplicating the existing command line
argument parsing code, which (a) makes it very easy for the
two to drift out of sync in future and (b) means command line
options added in future might end up without a corresponding
environment variable.

I think it would be much nicer to have this be table-driven,
to avoid the code duplication. It ought to be possible to
derive most of the extra --help text from the table too.

-- PMM

[Qemu-devel] [PATCH] introduce environment variables for all qemu-user options

[Johannes Schauer]

Rework option parsing code for linux-user in a table-driven manner to allow
environment variables for all commandline options.

Also generate usage() output from option table.



Signed-off-by: Johannes Schauer <j.schauer@email.de>
---
 linux-user/main.c |  518 ++++++++++++++++++++++++++++++++++-------------------
 1 files changed, 331 insertions(+), 187 deletions(-)

diff --git a/linux-user/main.c b/linux-user/main.c
index dbba8be..95e8651 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -40,6 +40,10 @@
 char *exec_path;
 
 int singlestep;
+const char *filename;
+const char *argv0 = NULL;
+int gdbstub_port = 0;
+const char *cpu_model;
 unsigned long mmap_min_addr;
 #if defined(CONFIG_USE_GUEST_BASE)
 unsigned long guest_base;
@@ -47,6 +51,8 @@ int have_guest_base;
 unsigned long reserved_va;
 #endif
 
+static void usage(void);
+
 static const char *interp_prefix = CONFIG_QEMU_INTERP_PREFIX;
 const char *qemu_uname_release = CONFIG_UNAME_RELEASE;
 
@@ -2624,50 +2630,6 @@ void cpu_loop (CPUState *env)
 }
 #endif /* TARGET_ALPHA */
 
-static void usage(void)
-{
-    printf("qemu-" TARGET_ARCH " version " QEMU_VERSION QEMU_PKGVERSION ", Copyright (c) 2003-2008 Fabrice Bellard\n"
-           "usage: qemu-" TARGET_ARCH " [options] program [arguments...]\n"
-           "Linux CPU emulator (compiled for %s emulation)\n"
-           "\n"
-           "Standard options:\n"
-           "-h                print this help\n"
-           "-g port           wait gdb connection to port\n"
-           "-L path           set the elf interpreter prefix (default=%s)\n"
-           "-s size           set the stack size in bytes (default=%ld)\n"
-           "-cpu model        select CPU (-cpu ? for list)\n"
-           "-drop-ld-preload  drop LD_PRELOAD for target process\n"
-           "-E var=value      sets/modifies targets environment variable(s)\n"
-           "-U var            unsets targets environment variable(s)\n"
-           "-0 argv0          forces target process argv[0] to be argv0\n"
-#if defined(CONFIG_USE_GUEST_BASE)
-           "-B address        set guest_base address to address\n"
-           "-R size           reserve size bytes for guest virtual address space\n"
-#endif
-           "\n"
-           "Debug options:\n"
-           "-d options   activate log (logfile=%s)\n"
-           "-p pagesize  set the host page size to 'pagesize'\n"
-           "-singlestep  always run in singlestep mode\n"
-           "-strace      log system calls\n"
-           "\n"
-           "Environment variables:\n"
-           "QEMU_STRACE       Print system calls and arguments similar to the\n"
-           "                  'strace' program.  Enable by setting to any value.\n"
-           "You can use -E and -U options to set/unset environment variables\n"
-           "for target process.  It is possible to provide several variables\n"
-           "by repeating the option.  For example:\n"
-           "    -E var1=val2 -E var2=val2 -U LD_PRELOAD -U LD_DEBUG\n"
-           "Note that if you provide several changes to single variable\n"
-           "last change will stay in effect.\n"
-           ,
-           TARGET_ARCH,
-           interp_prefix,
-           guest_stack_size,
-           DEBUG_LOGFILE);
-    exit(1);
-}
-
 THREAD CPUState *thread_env;
 
 void task_settid(TaskState *ts)
@@ -2703,24 +2665,342 @@ void init_task_state(TaskState *ts)
     }
     ts->sigqueue_table[i].next = NULL;
 }
- 
+
+static void handle_arg_help(const char *arg, envlist_t *envlist)
+{
+    usage();
+}
+
+static void handle_arg_log(const char *arg, envlist_t *envlist)
+{
+    int mask;
+    const CPULogItem *item;
+
+    mask = cpu_str_to_log_mask(arg);
+    if (!mask) {
+        printf("Log items (comma separated):\n");
+        for(item = cpu_log_items; item->mask != 0; item++) {
+            printf("%-10s %s\n", item->name, item->help);
+        }
+        exit(1);
+    }
+    cpu_set_log(mask);
+}
+
+static void handle_arg_set_env(const char *arg, envlist_t *envlist)
+{
+    char *r, *p, *token;
+    r = p = strdup(arg);
+    while ((token = strsep(&p, ",")) != NULL) {
+        if (envlist_setenv(envlist, token) != 0)
+            usage();
+    }
+    free(r);
+}
+
+static void handle_arg_unset_env(const char *arg, envlist_t *envlist)
+{
+    char *r, *p, *token;
+    r = p = strdup(arg);
+    while ((token = strsep(&p, ",")) != NULL) {
+        if (envlist_unsetenv(envlist, token) != 0)
+            usage();
+    }
+    free(r);
+}
+
+static void handle_arg_argv0(const char *arg, envlist_t *envlist)
+{
+    argv0 = strdup(arg);
+}
+
+static void handle_arg_stack_size(const char *arg, envlist_t *envlist)
+{
+    char *p;
+    guest_stack_size = strtoul(arg, &p, 0);
+    if (guest_stack_size == 0)
+        usage();
+    if (*p == 'M')
+        guest_stack_size *= 1024 * 1024;
+    else if (*p == 'k' || *p == 'K')
+        guest_stack_size *= 1024;
+}
+
+static void handle_arg_ld_prefix(const char *arg, envlist_t *envlist)
+{
+    interp_prefix = strdup(arg);
+}
+
+static void handle_arg_pagesize(const char *arg, envlist_t *envlist)
+{
+    qemu_host_page_size = atoi(arg);
+    if (qemu_host_page_size == 0 ||
+        (qemu_host_page_size & (qemu_host_page_size - 1)) != 0) {
+        fprintf(stderr, "page size must be a power of two\n");
+        exit(1);
+    }
+}
+
+static void handle_arg_gdb(const char *arg, envlist_t *envlist)
+{
+    gdbstub_port = atoi(arg);
+}
+
+static void handle_arg_uname(const char *arg, envlist_t *envlist)
+{
+    qemu_uname_release = strdup(arg);
+}
+
+static void handle_arg_cpu(const char *arg, envlist_t *envlist)
+{
+    cpu_model = strdup(arg);
+    if (cpu_model == NULL || strcmp(cpu_model, "?") == 0) {
+/* XXX: implement xxx_cpu_list for targets that still miss it */
+#if defined(cpu_list_id)
+        cpu_list_id(stdout, &fprintf, "");
+#elif defined(cpu_list)
+        cpu_list(stdout, &fprintf); /* deprecated */
+#endif
+        exit(1);
+    }
+}
+
+#if defined(CONFIG_USE_GUEST_BASE)
+static void handle_arg_guest_base(const char *arg, envlist_t *envlist)
+{
+    guest_base = strtol(arg, NULL, 0);
+    have_guest_base = 1;
+}
+
+static void handle_arg_reserved_va(const char *arg, envlist_t *envlist)
+{
+    char *p;
+    int shift = 0;
+    reserved_va = strtoul(arg, &p, 0);
+    switch (*p) {
+    case 'k':
+    case 'K':
+        shift = 10;
+        break;
+    case 'M':
+        shift = 20;
+        break;
+    case 'G':
+        shift = 30;
+        break;
+    }
+    if (shift) {
+        unsigned long unshifted = reserved_va;
+        p++;
+        reserved_va <<= shift;
+        if (((reserved_va >> shift) != unshifted)
+#if HOST_LONG_BITS > TARGET_VIRT_ADDR_SPACE_BITS
+            || (reserved_va > (1ul << TARGET_VIRT_ADDR_SPACE_BITS))
+#endif
+            ) {
+            fprintf(stderr, "Reserved virtual address too big\n");
+            exit(1);
+        }
+    }
+    if (*p) {
+        fprintf(stderr, "Unrecognised -R size suffix '%s'\n", p);
+        exit(1);
+    }
+}
+#endif
+
+static void handle_arg_singlestep(const char *arg, envlist_t *envlist)
+{
+    singlestep = 1;
+}
+
+static void handle_arg_strace(const char *arg, envlist_t *envlist)
+{
+    do_strace = 1;
+}
+
+struct qemu_argument {
+    const char *argv;
+    const char *env;
+    bool has_arg;
+    void (*handle_opt)(const char *arg, envlist_t *envlist);
+    const char *example;
+    const char *help;
+};
+
+struct qemu_argument arg_table[] = {
+    {"h",          "",                 false, handle_arg_help,
+     "",           "print this help"},
+    {"g",          "QEMU_GDB",         true,  handle_arg_gdb,
+     "port",       "wait gdb connection to 'port'"},
+    {"L",          "QEMU_LD_PREFIX",   true,  handle_arg_ld_prefix,
+     "path",       "set the elf interpreter prefix to 'path'"},
+    {"s",          "QEMU_STACK_SIZE",  true,  handle_arg_stack_size,
+     "size",       "set the stack size to 'size' bytes"},
+    {"cpu",        "QEMU_CPU",         true,  handle_arg_cpu,
+     "model",      "select CPU (-cpu ? for list)"},
+    {"E",          "QEMU_SET_ENV",     true,  handle_arg_set_env,
+     "var=value",  "sets targets environment variable (see below)"},
+    {"U",          "QEMU_UNSET_ENV",   true,  handle_arg_unset_env,
+     "var",        "unsets targets environment variable (see below)"},
+    {"0",          "QEMU_ARGV0",       true,  handle_arg_argv0,
+     "argv0",      "forces target process argv[0] to be 'argv0'"},
+    {"r",          "QEMU_UNAME",       true,  handle_arg_uname,
+     "uname",      "set qemu uname release string to 'uname'"},
+#if defined(CONFIG_USE_GUEST_BASE)
+    {"B",          "QEMU_GUEST_BASE",  true,  handle_arg_guest_base,
+     "address",    "set guest_base address to 'address'"},
+    {"R",          "QEMU_RESERVED_VA", true,  handle_arg_reserved_va,
+     "size",       "reserve 'size' bytes for guest virtual address space"},
+#endif
+    {"d",          "QEMU_LOG",         true,  handle_arg_log,
+     "options",    "activate log"},
+    {"p",          "QEMU_PAGESIZE",    true,  handle_arg_pagesize,
+     "pagesize",   "set the host page size to 'pagesize'"},
+    {"singlestep", "QEMU_SINGLESTEP",  false, handle_arg_singlestep,
+     "",           "run in singlestep mode"},
+    {"strace",     "QEMU_STRACE",      false, handle_arg_strace,
+     "",           "log system calls"},
+    {NULL, NULL, false, NULL, NULL, NULL}
+};
+
+static void usage(void)
+{
+    struct qemu_argument *arginfo;
+    int maxarglen;
+    int maxenvlen;
+
+    printf("qemu-" TARGET_ARCH " version " QEMU_VERSION QEMU_PKGVERSION
+           ", Copyright (c) 2003-2008 Fabrice Bellard\n"
+           "usage: qemu-" TARGET_ARCH " [options] program [arguments...]\n"
+           "Linux CPU emulator (compiled for " TARGET_ARCH " emulation)\n"
+           "\n"
+           "Options and associated environment variables:\n"
+           "\n");
+
+    maxarglen = maxenvlen = 0;
+
+    for (arginfo = arg_table; arginfo->handle_opt != NULL; arginfo++) {
+        if (strlen(arginfo->env) > maxenvlen)
+            maxenvlen = strlen(arginfo->env);
+        if (strlen(arginfo->argv) > maxarglen)
+            maxarglen = strlen(arginfo->argv);
+    }
+
+    printf("%-*s%-*sDescription\n", maxarglen+3, "Argument",
+            maxenvlen+1, "Env-variable");
+
+    for (arginfo = arg_table; arginfo->handle_opt != NULL; arginfo++) {
+        if (arginfo->has_arg) {
+            printf("-%s %-*s %-*s %s\n", arginfo->argv,
+                    (int)(maxarglen-strlen(arginfo->argv)), arginfo->example,
+                    maxenvlen, arginfo->env, arginfo->help);
+        } else {
+            printf("-%-*s %-*s %s\n", maxarglen+1, arginfo->argv,
+                    maxenvlen, arginfo->env,
+                    arginfo->help);
+        }
+    }
+
+    printf("\n"
+           "Defaults:\n"
+           "QEMU_LD_PREFIX  = %s\n"
+           "QEMU_STACK_SIZE = %ld byte\n"
+           "QEMU_LOG        = %s\n",
+           interp_prefix,
+           guest_stack_size,
+           DEBUG_LOGFILE);
+
+    printf("\n"
+           "You can use -E and -U options or the QEMU_SET_ENV and\n"
+           "QEMU_UNSET_ENV environment variables to set and unset\n"
+           "environment variables for the target process.\n"
+           "It is possible to provide several variables by separating them\n"
+           "by commas in getsubopt(3) style. Additionally it is possible to\n"
+           "provide the -E and -U options multiple times.\n"
+           "The following lines are equivalent:\n"
+           "    -E var1=val2 -E var2=val2 -U LD_PRELOAD -U LD_DEBUG\n"
+           "    -E var1=val2,var2=val2 -U LD_PRELOAD,LD_DEBUG\n"
+           "    QEMU_SET_ENV=var1=val2,var2=val2 QEMU_UNSET_ENV=LD_PRELOAD,LD_DEBUG\n"
+           "Note that if you provide several changes to a single variable\n"
+           "the last change will stay in effect.\n");
+
+    exit(1);
+}
+
+static int parse_args(int argc, char **argv, envlist_t *envlist)
+{
+    const char *r;
+    int optind;
+    struct qemu_argument *arginfo;
+
+    for (arginfo = arg_table; arginfo->handle_opt != NULL; arginfo++) {
+        if (arginfo->env == NULL) {
+            continue;
+        }
+
+        if ((r = getenv(arginfo->env)) != NULL) {
+            arginfo->handle_opt(r, envlist);
+        }
+    }
+
+    optind = 1;
+    for(;;) {
+        if (optind >= argc)
+            break;
+        r = argv[optind];
+        if (r[0] != '-')
+            break;
+        optind++;
+        r++;
+        if (!strcmp(r, "-")) {
+            break;
+        }
+
+        for (arginfo = arg_table; arginfo->handle_opt != NULL; arginfo++) {
+            if (!strcmp(r, arginfo->argv)) {
+                if (optind >= argc) {
+                    usage();
+                }
+
+                arginfo->handle_opt(argv[optind], envlist);
+
+                if (arginfo->has_arg) {
+                    optind++;
+                }
+
+                break;
+            }
+        }
+
+        // no option matched the current argv
+        if (arginfo->handle_opt == NULL) {
+            usage();
+        }
+    }
+
+    if (optind >= argc) {
+        usage();
+    }
+
+    filename = argv[optind];
+    exec_path = argv[optind];
+
+    return optind;
+}
+
 int main(int argc, char **argv, char **envp)
 {
-    const char *filename;
-    const char *cpu_model;
     struct target_pt_regs regs1, *regs = &regs1;
     struct image_info info1, *info = &info1;
     struct linux_binprm bprm;
     TaskState ts1, *ts = &ts1;
     CPUState *env;
     int optind;
-    const char *r;
-    int gdbstub_port = 0;
     char **target_environ, **wrk;
     char **target_argv;
     int target_argc;
     envlist_t *envlist = NULL;
-    const char *argv0 = NULL;
     int i;
     int ret;
 
@@ -2758,143 +3038,7 @@ int main(int argc, char **argv, char **envp)
     cpudef_setup(); /* parse cpu definitions in target config file (TBD) */
 #endif
 
-    optind = 1;
-    for(;;) {
-        if (optind >= argc)
-            break;
-        r = argv[optind];
-        if (r[0] != '-')
-            break;
-        optind++;
-        r++;
-        if (!strcmp(r, "-")) {
-            break;
-        } else if (!strcmp(r, "d")) {
-            int mask;
-            const CPULogItem *item;
-
-	    if (optind >= argc)
-		break;
-
-	    r = argv[optind++];
-            mask = cpu_str_to_log_mask(r);
-            if (!mask) {
-                printf("Log items (comma separated):\n");
-                for(item = cpu_log_items; item->mask != 0; item++) {
-                    printf("%-10s %s\n", item->name, item->help);
-                }
-                exit(1);
-            }
-            cpu_set_log(mask);
-        } else if (!strcmp(r, "E")) {
-            r = argv[optind++];
-            if (envlist_setenv(envlist, r) != 0)
-                usage();
-        } else if (!strcmp(r, "ignore-environment")) {
-            envlist_free(envlist);
-            if ((envlist = envlist_create()) == NULL) {
-                (void) fprintf(stderr, "Unable to allocate envlist\n");
-                exit(1);
-            }
-        } else if (!strcmp(r, "U")) {
-            r = argv[optind++];
-            if (envlist_unsetenv(envlist, r) != 0)
-                usage();
-        } else if (!strcmp(r, "0")) {
-            r = argv[optind++];
-            argv0 = r;
-        } else if (!strcmp(r, "s")) {
-            if (optind >= argc)
-                break;
-            r = argv[optind++];
-            guest_stack_size = strtoul(r, (char **)&r, 0);
-            if (guest_stack_size == 0)
-                usage();
-            if (*r == 'M')
-                guest_stack_size *= 1024 * 1024;
-            else if (*r == 'k' || *r == 'K')
-                guest_stack_size *= 1024;
-        } else if (!strcmp(r, "L")) {
-            interp_prefix = argv[optind++];
-        } else if (!strcmp(r, "p")) {
-            if (optind >= argc)
-                break;
-            qemu_host_page_size = atoi(argv[optind++]);
-            if (qemu_host_page_size == 0 ||
-                (qemu_host_page_size & (qemu_host_page_size - 1)) != 0) {
-                fprintf(stderr, "page size must be a power of two\n");
-                exit(1);
-            }
-        } else if (!strcmp(r, "g")) {
-            if (optind >= argc)
-                break;
-            gdbstub_port = atoi(argv[optind++]);
-	} else if (!strcmp(r, "r")) {
-	    qemu_uname_release = argv[optind++];
-        } else if (!strcmp(r, "cpu")) {
-            cpu_model = argv[optind++];
-            if (cpu_model == NULL || strcmp(cpu_model, "?") == 0) {
-/* XXX: implement xxx_cpu_list for targets that still miss it */
-#if defined(cpu_list_id)
-                cpu_list_id(stdout, &fprintf, "");
-#elif defined(cpu_list)
-                cpu_list(stdout, &fprintf); /* deprecated */
-#endif
-                exit(1);
-            }
-#if defined(CONFIG_USE_GUEST_BASE)
-        } else if (!strcmp(r, "B")) {
-           guest_base = strtol(argv[optind++], NULL, 0);
-           have_guest_base = 1;
-        } else if (!strcmp(r, "R")) {
-            char *p;
-            int shift = 0;
-            reserved_va = strtoul(argv[optind++], &p, 0);
-            switch (*p) {
-            case 'k':
-            case 'K':
-                shift = 10;
-                break;
-            case 'M':
-                shift = 20;
-                break;
-            case 'G':
-                shift = 30;
-                break;
-            }
-            if (shift) {
-                unsigned long unshifted = reserved_va;
-                p++;
-                reserved_va <<= shift;
-                if (((reserved_va >> shift) != unshifted)
-#if HOST_LONG_BITS > TARGET_VIRT_ADDR_SPACE_BITS
-                    || (reserved_va > (1ul << TARGET_VIRT_ADDR_SPACE_BITS))
-#endif
-                    ) {
-                    fprintf(stderr, "Reserved virtual address too big\n");
-                    exit(1);
-                }
-            }
-            if (*p) {
-                fprintf(stderr, "Unrecognised -R size suffix '%s'\n", p);
-                exit(1);
-            }
-#endif
-        } else if (!strcmp(r, "drop-ld-preload")) {
-            (void) envlist_unsetenv(envlist, "LD_PRELOAD");
-        } else if (!strcmp(r, "singlestep")) {
-            singlestep = 1;
-        } else if (!strcmp(r, "strace")) {
-            do_strace = 1;
-        } else
-        {
-            usage();
-        }
-    }
-    if (optind >= argc)
-        usage();
-    filename = argv[optind];
-    exec_path = argv[optind];
+    optind = parse_args(argc, argv, envlist);
 
     /* Zero out regs */
     memset(regs, 0, sizeof(struct target_pt_regs));
-- 
1.7.5.4

Re: [Qemu-devel] [PATCH] introduce environment variables for all qemu-user options

[Peter Maydell]

On 31 July 2011 22:40, Johannes Schauer <j.schauer@email.de> wrote:
> Rework option parsing code for linux-user in a table-driven manner to allow
> environment variables for all commandline options.
>
> Also generate usage() output from option table.

Thanks for this, it looks good. A couple of minor points:
(1) what's the rationale for having most of the things the
arg-parsing-functions change be global variables but passing
envlist as an argument to each function? It's only used by
two of the functions so maybe that should just be a global too.
(2) scripts/checkpatch.pl complains about a number of formatting
nits; mostly these are in existing code you've just moved around,
but I think it's worth fixing them in passing anyway.

-- PMM

[Qemu-devel] [PATCH] introduce environment variables for all qemu-user options

[Johannes Schauer]

Rework option parsing code for linux-user in a table-driven manner to allow
environment variables for all commandline options.

Also generate usage() output from option table.

Fix complains from checkpatch.pl, also have envlist global


Signed-off-by: Johannes Schauer <j.schauer@email.de>
---
 linux-user/main.c |  530 ++++++++++++++++++++++++++++++++++-------------------
 1 files changed, 342 insertions(+), 188 deletions(-)

diff --git a/linux-user/main.c b/linux-user/main.c
index dbba8be..74c5198 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -40,6 +40,11 @@
 char *exec_path;
 
 int singlestep;
+const char *filename;
+const char *argv0;
+int gdbstub_port;
+envlist_t *envlist;
+const char *cpu_model;
 unsigned long mmap_min_addr;
 #if defined(CONFIG_USE_GUEST_BASE)
 unsigned long guest_base;
@@ -47,6 +52,8 @@ int have_guest_base;
 unsigned long reserved_va;
 #endif
 
+static void usage(void);
+
 static const char *interp_prefix = CONFIG_QEMU_INTERP_PREFIX;
 const char *qemu_uname_release = CONFIG_UNAME_RELEASE;
 
@@ -2624,50 +2631,6 @@ void cpu_loop (CPUState *env)
 }
 #endif /* TARGET_ALPHA */
 
-static void usage(void)
-{
-    printf("qemu-" TARGET_ARCH " version " QEMU_VERSION QEMU_PKGVERSION ", Copyright (c) 2003-2008 Fabrice Bellard\n"
-           "usage: qemu-" TARGET_ARCH " [options] program [arguments...]\n"
-           "Linux CPU emulator (compiled for %s emulation)\n"
-           "\n"
-           "Standard options:\n"
-           "-h                print this help\n"
-           "-g port           wait gdb connection to port\n"
-           "-L path           set the elf interpreter prefix (default=%s)\n"
-           "-s size           set the stack size in bytes (default=%ld)\n"
-           "-cpu model        select CPU (-cpu ? for list)\n"
-           "-drop-ld-preload  drop LD_PRELOAD for target process\n"
-           "-E var=value      sets/modifies targets environment variable(s)\n"
-           "-U var            unsets targets environment variable(s)\n"
-           "-0 argv0          forces target process argv[0] to be argv0\n"
-#if defined(CONFIG_USE_GUEST_BASE)
-           "-B address        set guest_base address to address\n"
-           "-R size           reserve size bytes for guest virtual address space\n"
-#endif
-           "\n"
-           "Debug options:\n"
-           "-d options   activate log (logfile=%s)\n"
-           "-p pagesize  set the host page size to 'pagesize'\n"
-           "-singlestep  always run in singlestep mode\n"
-           "-strace      log system calls\n"
-           "\n"
-           "Environment variables:\n"
-           "QEMU_STRACE       Print system calls and arguments similar to the\n"
-           "                  'strace' program.  Enable by setting to any value.\n"
-           "You can use -E and -U options to set/unset environment variables\n"
-           "for target process.  It is possible to provide several variables\n"
-           "by repeating the option.  For example:\n"
-           "    -E var1=val2 -E var2=val2 -U LD_PRELOAD -U LD_DEBUG\n"
-           "Note that if you provide several changes to single variable\n"
-           "last change will stay in effect.\n"
-           ,
-           TARGET_ARCH,
-           interp_prefix,
-           guest_stack_size,
-           DEBUG_LOGFILE);
-    exit(1);
-}
-
 THREAD CPUState *thread_env;
 
 void task_settid(TaskState *ts)
@@ -2703,24 +2666,351 @@ void init_task_state(TaskState *ts)
     }
     ts->sigqueue_table[i].next = NULL;
 }
- 
+
+static void handle_arg_help(const char *arg)
+{
+    usage();
+}
+
+static void handle_arg_log(const char *arg)
+{
+    int mask;
+    const CPULogItem *item;
+
+    mask = cpu_str_to_log_mask(arg);
+    if (!mask) {
+        printf("Log items (comma separated):\n");
+        for (item = cpu_log_items; item->mask != 0; item++) {
+            printf("%-10s %s\n", item->name, item->help);
+        }
+        exit(1);
+    }
+    cpu_set_log(mask);
+}
+
+static void handle_arg_set_env(const char *arg)
+{
+    char *r, *p, *token;
+    r = p = strdup(arg);
+    while ((token = strsep(&p, ",")) != NULL) {
+        if (envlist_setenv(envlist, token) != 0) {
+            usage();
+        }
+    }
+    free(r);
+}
+
+static void handle_arg_unset_env(const char *arg)
+{
+    char *r, *p, *token;
+    r = p = strdup(arg);
+    while ((token = strsep(&p, ",")) != NULL) {
+        if (envlist_unsetenv(envlist, token) != 0) {
+            usage();
+        }
+    }
+    free(r);
+}
+
+static void handle_arg_argv0(const char *arg)
+{
+    argv0 = strdup(arg);
+}
+
+static void handle_arg_stack_size(const char *arg)
+{
+    char *p;
+    guest_stack_size = strtoul(arg, &p, 0);
+    if (guest_stack_size == 0) {
+        usage();
+    }
+
+    if (*p == 'M') {
+        guest_stack_size *= 1024 * 1024;
+    } else if (*p == 'k' || *p == 'K') {
+        guest_stack_size *= 1024;
+    }
+}
+
+static void handle_arg_ld_prefix(const char *arg)
+{
+    interp_prefix = strdup(arg);
+}
+
+static void handle_arg_pagesize(const char *arg)
+{
+    qemu_host_page_size = atoi(arg);
+    if (qemu_host_page_size == 0 ||
+        (qemu_host_page_size & (qemu_host_page_size - 1)) != 0) {
+        fprintf(stderr, "page size must be a power of two\n");
+        exit(1);
+    }
+}
+
+static void handle_arg_gdb(const char *arg)
+{
+    gdbstub_port = atoi(arg);
+}
+
+static void handle_arg_uname(const char *arg)
+{
+    qemu_uname_release = strdup(arg);
+}
+
+static void handle_arg_cpu(const char *arg)
+{
+    cpu_model = strdup(arg);
+    if (cpu_model == NULL || strcmp(cpu_model, "?") == 0) {
+        /* XXX: implement xxx_cpu_list for targets that still miss it */
+#if defined(cpu_list_id)
+        cpu_list_id(stdout, &fprintf, "");
+#elif defined(cpu_list)
+        cpu_list(stdout, &fprintf); /* deprecated */
+#endif
+        exit(1);
+    }
+}
+
+#if defined(CONFIG_USE_GUEST_BASE)
+static void handle_arg_guest_base(const char *arg)
+{
+    guest_base = strtol(arg, NULL, 0);
+    have_guest_base = 1;
+}
+
+static void handle_arg_reserved_va(const char *arg)
+{
+    char *p;
+    int shift = 0;
+    reserved_va = strtoul(arg, &p, 0);
+    switch (*p) {
+    case 'k':
+    case 'K':
+        shift = 10;
+        break;
+    case 'M':
+        shift = 20;
+        break;
+    case 'G':
+        shift = 30;
+        break;
+    }
+    if (shift) {
+        unsigned long unshifted = reserved_va;
+        p++;
+        reserved_va <<= shift;
+        if (((reserved_va >> shift) != unshifted)
+#if HOST_LONG_BITS > TARGET_VIRT_ADDR_SPACE_BITS
+            || (reserved_va > (1ul << TARGET_VIRT_ADDR_SPACE_BITS))
+#endif
+            ) {
+            fprintf(stderr, "Reserved virtual address too big\n");
+            exit(1);
+        }
+    }
+    if (*p) {
+        fprintf(stderr, "Unrecognised -R size suffix '%s'\n", p);
+        exit(1);
+    }
+}
+#endif
+
+static void handle_arg_singlestep(const char *arg)
+{
+    singlestep = 1;
+}
+
+static void handle_arg_strace(const char *arg)
+{
+    do_strace = 1;
+}
+
+struct qemu_argument {
+    const char *argv;
+    const char *env;
+    bool has_arg;
+    void (*handle_opt)(const char *arg);
+    const char *example;
+    const char *help;
+};
+
+struct qemu_argument arg_table[] = {
+    {"h",          "",                 false, handle_arg_help,
+     "",           "print this help"},
+    {"g",          "QEMU_GDB",         true,  handle_arg_gdb,
+     "port",       "wait gdb connection to 'port'"},
+    {"L",          "QEMU_LD_PREFIX",   true,  handle_arg_ld_prefix,
+     "path",       "set the elf interpreter prefix to 'path'"},
+    {"s",          "QEMU_STACK_SIZE",  true,  handle_arg_stack_size,
+     "size",       "set the stack size to 'size' bytes"},
+    {"cpu",        "QEMU_CPU",         true,  handle_arg_cpu,
+     "model",      "select CPU (-cpu ? for list)"},
+    {"E",          "QEMU_SET_ENV",     true,  handle_arg_set_env,
+     "var=value",  "sets targets environment variable (see below)"},
+    {"U",          "QEMU_UNSET_ENV",   true,  handle_arg_unset_env,
+     "var",        "unsets targets environment variable (see below)"},
+    {"0",          "QEMU_ARGV0",       true,  handle_arg_argv0,
+     "argv0",      "forces target process argv[0] to be 'argv0'"},
+    {"r",          "QEMU_UNAME",       true,  handle_arg_uname,
+     "uname",      "set qemu uname release string to 'uname'"},
+#if defined(CONFIG_USE_GUEST_BASE)
+    {"B",          "QEMU_GUEST_BASE",  true,  handle_arg_guest_base,
+     "address",    "set guest_base address to 'address'"},
+    {"R",          "QEMU_RESERVED_VA", true,  handle_arg_reserved_va,
+     "size",       "reserve 'size' bytes for guest virtual address space"},
+#endif
+    {"d",          "QEMU_LOG",         true,  handle_arg_log,
+     "options",    "activate log"},
+    {"p",          "QEMU_PAGESIZE",    true,  handle_arg_pagesize,
+     "pagesize",   "set the host page size to 'pagesize'"},
+    {"singlestep", "QEMU_SINGLESTEP",  false, handle_arg_singlestep,
+     "",           "run in singlestep mode"},
+    {"strace",     "QEMU_STRACE",      false, handle_arg_strace,
+     "",           "log system calls"},
+    {NULL, NULL, false, NULL, NULL, NULL}
+};
+
+static void usage(void)
+{
+    struct qemu_argument *arginfo;
+    int maxarglen;
+    int maxenvlen;
+
+    printf("qemu-" TARGET_ARCH " version " QEMU_VERSION QEMU_PKGVERSION
+           ", Copyright (c) 2003-2008 Fabrice Bellard\n"
+           "usage: qemu-" TARGET_ARCH " [options] program [arguments...]\n"
+           "Linux CPU emulator (compiled for " TARGET_ARCH " emulation)\n"
+           "\n"
+           "Options and associated environment variables:\n"
+           "\n");
+
+    maxarglen = maxenvlen = 0;
+
+    for (arginfo = arg_table; arginfo->handle_opt != NULL; arginfo++) {
+        if (strlen(arginfo->env) > maxenvlen) {
+            maxenvlen = strlen(arginfo->env);
+        }
+        if (strlen(arginfo->argv) > maxarglen) {
+            maxarglen = strlen(arginfo->argv);
+        }
+    }
+
+    printf("%-*s%-*sDescription\n", maxarglen+3, "Argument",
+            maxenvlen+1, "Env-variable");
+
+    for (arginfo = arg_table; arginfo->handle_opt != NULL; arginfo++) {
+        if (arginfo->has_arg) {
+            printf("-%s %-*s %-*s %s\n", arginfo->argv,
+                    (int)(maxarglen-strlen(arginfo->argv)), arginfo->example,
+                    maxenvlen, arginfo->env, arginfo->help);
+        } else {
+            printf("-%-*s %-*s %s\n", maxarglen+1, arginfo->argv,
+                    maxenvlen, arginfo->env,
+                    arginfo->help);
+        }
+    }
+
+    printf("\n"
+           "Defaults:\n"
+           "QEMU_LD_PREFIX  = %s\n"
+           "QEMU_STACK_SIZE = %ld byte\n"
+           "QEMU_LOG        = %s\n",
+           interp_prefix,
+           guest_stack_size,
+           DEBUG_LOGFILE);
+
+    printf("\n"
+           "You can use -E and -U options or the QEMU_SET_ENV and\n"
+           "QEMU_UNSET_ENV environment variables to set and unset\n"
+           "environment variables for the target process.\n"
+           "It is possible to provide several variables by separating them\n"
+           "by commas in getsubopt(3) style. Additionally it is possible to\n"
+           "provide the -E and -U options multiple times.\n"
+           "The following lines are equivalent:\n"
+           "    -E var1=val2 -E var2=val2 -U LD_PRELOAD -U LD_DEBUG\n"
+           "    -E var1=val2,var2=val2 -U LD_PRELOAD,LD_DEBUG\n"
+           "    QEMU_SET_ENV=var1=val2,var2=val2 QEMU_UNSET_ENV=LD_PRELOAD,LD_DEBUG\n"
+           "Note that if you provide several changes to a single variable\n"
+           "the last change will stay in effect.\n");
+
+    exit(1);
+}
+
+static int parse_args(int argc, char **argv)
+{
+    const char *r;
+    int optind;
+    struct qemu_argument *arginfo;
+
+    for (arginfo = arg_table; arginfo->handle_opt != NULL; arginfo++) {
+        if (arginfo->env == NULL) {
+            continue;
+        }
+
+        r = getenv(arginfo->env);
+        if (r != NULL) {
+            arginfo->handle_opt(r);
+        }
+    }
+
+    optind = 1;
+    for (;;) {
+        if (optind >= argc) {
+            break;
+        }
+        r = argv[optind];
+        if (r[0] != '-') {
+            break;
+        }
+        optind++;
+        r++;
+        if (!strcmp(r, "-")) {
+            break;
+        }
+
+        for (arginfo = arg_table; arginfo->handle_opt != NULL; arginfo++) {
+            if (!strcmp(r, arginfo->argv)) {
+                if (optind >= argc) {
+                    usage();
+                }
+
+                arginfo->handle_opt(argv[optind]);
+
+                if (arginfo->has_arg) {
+                    optind++;
+                }
+
+                break;
+            }
+        }
+
+        /* no option matched the current argv */
+        if (arginfo->handle_opt == NULL) {
+            usage();
+        }
+    }
+
+    if (optind >= argc) {
+        usage();
+    }
+
+    filename = argv[optind];
+    exec_path = argv[optind];
+
+    return optind;
+}
+
 int main(int argc, char **argv, char **envp)
 {
-    const char *filename;
-    const char *cpu_model;
     struct target_pt_regs regs1, *regs = &regs1;
     struct image_info info1, *info = &info1;
     struct linux_binprm bprm;
     TaskState ts1, *ts = &ts1;
     CPUState *env;
     int optind;
-    const char *r;
-    int gdbstub_port = 0;
     char **target_environ, **wrk;
     char **target_argv;
     int target_argc;
-    envlist_t *envlist = NULL;
-    const char *argv0 = NULL;
     int i;
     int ret;
 
@@ -2758,143 +3048,7 @@ int main(int argc, char **argv, char **envp)
     cpudef_setup(); /* parse cpu definitions in target config file (TBD) */
 #endif
 
-    optind = 1;
-    for(;;) {
-        if (optind >= argc)
-            break;
-        r = argv[optind];
-        if (r[0] != '-')
-            break;
-        optind++;
-        r++;
-        if (!strcmp(r, "-")) {
-            break;
-        } else if (!strcmp(r, "d")) {
-            int mask;
-            const CPULogItem *item;
-
-	    if (optind >= argc)
-		break;
-
-	    r = argv[optind++];
-            mask = cpu_str_to_log_mask(r);
-            if (!mask) {
-                printf("Log items (comma separated):\n");
-                for(item = cpu_log_items; item->mask != 0; item++) {
-                    printf("%-10s %s\n", item->name, item->help);
-                }
-                exit(1);
-            }
-            cpu_set_log(mask);
-        } else if (!strcmp(r, "E")) {
-            r = argv[optind++];
-            if (envlist_setenv(envlist, r) != 0)
-                usage();
-        } else if (!strcmp(r, "ignore-environment")) {
-            envlist_free(envlist);
-            if ((envlist = envlist_create()) == NULL) {
-                (void) fprintf(stderr, "Unable to allocate envlist\n");
-                exit(1);
-            }
-        } else if (!strcmp(r, "U")) {
-            r = argv[optind++];
-            if (envlist_unsetenv(envlist, r) != 0)
-                usage();
-        } else if (!strcmp(r, "0")) {
-            r = argv[optind++];
-            argv0 = r;
-        } else if (!strcmp(r, "s")) {
-            if (optind >= argc)
-                break;
-            r = argv[optind++];
-            guest_stack_size = strtoul(r, (char **)&r, 0);
-            if (guest_stack_size == 0)
-                usage();
-            if (*r == 'M')
-                guest_stack_size *= 1024 * 1024;
-            else if (*r == 'k' || *r == 'K')
-                guest_stack_size *= 1024;
-        } else if (!strcmp(r, "L")) {
-            interp_prefix = argv[optind++];
-        } else if (!strcmp(r, "p")) {
-            if (optind >= argc)
-                break;
-            qemu_host_page_size = atoi(argv[optind++]);
-            if (qemu_host_page_size == 0 ||
-                (qemu_host_page_size & (qemu_host_page_size - 1)) != 0) {
-                fprintf(stderr, "page size must be a power of two\n");
-                exit(1);
-            }
-        } else if (!strcmp(r, "g")) {
-            if (optind >= argc)
-                break;
-            gdbstub_port = atoi(argv[optind++]);
-	} else if (!strcmp(r, "r")) {
-	    qemu_uname_release = argv[optind++];
-        } else if (!strcmp(r, "cpu")) {
-            cpu_model = argv[optind++];
-            if (cpu_model == NULL || strcmp(cpu_model, "?") == 0) {
-/* XXX: implement xxx_cpu_list for targets that still miss it */
-#if defined(cpu_list_id)
-                cpu_list_id(stdout, &fprintf, "");
-#elif defined(cpu_list)
-                cpu_list(stdout, &fprintf); /* deprecated */
-#endif
-                exit(1);
-            }
-#if defined(CONFIG_USE_GUEST_BASE)
-        } else if (!strcmp(r, "B")) {
-           guest_base = strtol(argv[optind++], NULL, 0);
-           have_guest_base = 1;
-        } else if (!strcmp(r, "R")) {
-            char *p;
-            int shift = 0;
-            reserved_va = strtoul(argv[optind++], &p, 0);
-            switch (*p) {
-            case 'k':
-            case 'K':
-                shift = 10;
-                break;
-            case 'M':
-                shift = 20;
-                break;
-            case 'G':
-                shift = 30;
-                break;
-            }
-            if (shift) {
-                unsigned long unshifted = reserved_va;
-                p++;
-                reserved_va <<= shift;
-                if (((reserved_va >> shift) != unshifted)
-#if HOST_LONG_BITS > TARGET_VIRT_ADDR_SPACE_BITS
-                    || (reserved_va > (1ul << TARGET_VIRT_ADDR_SPACE_BITS))
-#endif
-                    ) {
-                    fprintf(stderr, "Reserved virtual address too big\n");
-                    exit(1);
-                }
-            }
-            if (*p) {
-                fprintf(stderr, "Unrecognised -R size suffix '%s'\n", p);
-                exit(1);
-            }
-#endif
-        } else if (!strcmp(r, "drop-ld-preload")) {
-            (void) envlist_unsetenv(envlist, "LD_PRELOAD");
-        } else if (!strcmp(r, "singlestep")) {
-            singlestep = 1;
-        } else if (!strcmp(r, "strace")) {
-            do_strace = 1;
-        } else
-        {
-            usage();
-        }
-    }
-    if (optind >= argc)
-        usage();
-    filename = argv[optind];
-    exec_path = argv[optind];
+    optind = parse_args(argc, argv);
 
     /* Zero out regs */
     memset(regs, 0, sizeof(struct target_pt_regs));
-- 
1.7.5.4

Re: [Qemu-devel] [PATCH] introduce environment variables for all qemu-user options

[Yann Dirson]

This patch will be useful, but there is a security problem in its
current form.  The qemu-user-static package installs binfmt-misc
entries with "flags: OC", which makes the binary honor setuid bits.

Regardless of whether it is a good idea or not, the envvars ought to
be ignored in such a case.  Some clever checks using getresuid(), or
just geteuid() and getuid() when getresuid() is not available, surely
have to done.  There is probably some existing code for this in other
programs...

Best regards,
-- 
Yann

[Qemu-devel] [PATCH] add QEMU_LD_PREFIX environment variable

[Johannes Schauer]

Signed-off-by: Johannes Schauer <j.schauer@email.de>
---
 linux-user/main.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/linux-user/main.c b/linux-user/main.c
index 289054b..b590aa7 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -2891,6 +2891,11 @@ int main(int argc, char **argv, char **envp)
     cpudef_setup(); /* parse cpu definitions in target config file (TBD) */
 #endif
 
+    /* read interp_prefix from environment variable */
+    if (getenv("QEMU_LD_PREFIX") != NULL) {
+        interp_prefix = getenv("QEMU_LD_PREFIX");
+    }
+
     optind = 1;
     for(;;) {
         if (optind >= argc)
-- 
1.7.5.4

[Qemu-devel] [PATCH] add QEMU_LD_PREFIX environment variable

[Johannes Schauer]

Hi,

qemu allows to specify the elf interpreter prefix with the -L option. When
using qemu user mode emulation through the binfmt mechanism, it is not
possible to pass any commandline arguments to qemu. Having qemu evaluate an
environment variable makes it possible to still supply a custom elf
interpreter prefix, even if qemu is executed by the binfmt mechanism.

My motivation is an emdebian project which creates foreign debian
bootstraps. Since foreign binaries are executed without an explicit
qemu-user call but by the binfmt mechanism, it relied on having appropriate
content in /etc/qemu-binfmt/$arch/ which is the default elf interpreter
prefix path on debian. The downside currently is, that the shared libraries
in /etc/qemu-binfmt/$arch/ have to be adapted very often for different
debian systems running on the same qemu $arch. This could be avoided by
setting the proposed environment variable QEMU_LD_PREFIX to the just
created debian rootfs. As mentioned earlier, the usage of the -L option
is not possible in this scenario because qemu-user is only implicitly
called by the binfmt mechanism.

Hopefully this change can be applied.

thanks!

cheers, josch

Johannes Schauer (1):
  add QEMU_LD_PREFIX environment variable

 linux-user/main.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

-- 
1.7.5.4