Re: [PATCH V1 17/32] util: env var helpers

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Steve Sistare (steven.sistare@oracle.com) wrote:
> Add functions for saving fd's and ram extents in the environment via
> setenv, and for reading them back via getenv.
> 
> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
> Signed-off-by: Mark Kanda <mark.kanda@oracle.com>

This is an awful lot of env stuff - how about dumping
all this stuff into a file and reloading it?

Dave

> ---
>  MAINTAINERS           |   7 +++
>  include/qemu/cutils.h |   1 +
>  include/qemu/env.h    |  31 ++++++++++++
>  util/Makefile.objs    |   2 +-
>  util/env.c            | 132 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  5 files changed, 172 insertions(+), 1 deletion(-)
>  create mode 100644 include/qemu/env.h
>  create mode 100644 util/env.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 3395abd..8d377a7 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -3115,3 +3115,10 @@ Performance Tools and Tests
>  M: Ahmed Karaman <ahmedkhaledkaraman@gmail.com>
>  S: Maintained
>  F: scripts/performance/
> +
> +Environment variable helpers
> +M: Steve Sistare <steven.sistare@oracle.com>
> +M: Mark Kanda <mark.kanda@oracle.com>
> +S: Maintained
> +F: include/qemu/env.h
> +F: util/env.c
> diff --git a/include/qemu/cutils.h b/include/qemu/cutils.h
> index eb59852..d4c7d70 100644
> --- a/include/qemu/cutils.h
> +++ b/include/qemu/cutils.h
> @@ -1,6 +1,7 @@
>  #ifndef QEMU_CUTILS_H
>  #define QEMU_CUTILS_H
>  
> +#include "qemu/env.h"
>  /**
>   * pstrcpy:
>   * @buf: buffer to copy string into
> diff --git a/include/qemu/env.h b/include/qemu/env.h
> new file mode 100644
> index 0000000..53cc121
> --- /dev/null
> +++ b/include/qemu/env.h
> @@ -0,0 +1,31 @@
> +/*
> + * Copyright (c) 2020 Oracle and/or its affiliates.
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2.
> + * See the COPYING file in the top-level directory.
> + *
> + */
> +
> +#ifndef QEMU_ENV_H
> +#define QEMU_ENV_H
> +
> +#define FD_PREFIX "QEMU_FD_"
> +#define ADDR_PREFIX "QEMU_ADDR_"
> +#define LEN_PREFIX "QEMU_LEN_"
> +#define BOOL_PREFIX "QEMU_BOOL_"
> +
> +typedef int (*walkenv_cb)(const char *name, const char *val, void *handle);
> +
> +bool getenv_ram(const char *name, void **addrp, size_t *lenp);
> +void setenv_ram(const char *name, void *addr, size_t len);
> +void unsetenv_ram(const char *name);
> +int getenv_fd(const char *name);
> +void setenv_fd(const char *name, int fd);
> +void unsetenv_fd(const char *name);
> +bool getenv_bool(const char *name);
> +void setenv_bool(const char *name, bool val);
> +void unsetenv_bool(const char *name);
> +int walkenv(const char *prefix, walkenv_cb cb, void *handle);
> +void printenv(void);
> +
> +#endif
> diff --git a/util/Makefile.objs b/util/Makefile.objs
> index cc5e371..d357932 100644
> --- a/util/Makefile.objs
> +++ b/util/Makefile.objs
> @@ -1,4 +1,4 @@
> -util-obj-y = osdep.o cutils.o unicode.o qemu-timer-common.o
> +util-obj-y = osdep.o cutils.o unicode.o qemu-timer-common.o env.o
>  util-obj-$(call lnot,$(CONFIG_ATOMIC64)) += atomic64.o
>  util-obj-$(CONFIG_POSIX) += aio-posix.o
>  util-obj-$(CONFIG_POSIX) += fdmon-poll.o
> diff --git a/util/env.c b/util/env.c
> new file mode 100644
> index 0000000..0cc4a9f
> --- /dev/null
> +++ b/util/env.c
> @@ -0,0 +1,132 @@
> +/*
> + * Copyright (c) 2020 Oracle and/or its affiliates.
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2.
> + * See the COPYING file in the top-level directory.
> + *
> + */
> +
> +#include "qemu/osdep.h"
> +#include "qemu/env.h"
> +
> +static uint64_t getenv_ulong(const char *prefix, const char *name, bool *found)
> +{
> +    char var[80], *val;
> +    uint64_t res;
> +
> +    snprintf(var, sizeof(var), "%s%s", prefix, name);
> +    val = getenv(var);
> +    if (val) {
> +        *found = true;
> +        res = strtol(val, 0, 10);
> +    } else {
> +        *found = false;
> +        res = 0;
> +    }
> +    return res;
> +}
> +
> +static void setenv_ulong(const char *prefix, const char *name, uint64_t val)
> +{
> +    char var[80], val_str[80];
> +    snprintf(var, sizeof(var), "%s%s", prefix, name);
> +    snprintf(val_str, sizeof(val_str), "%"PRIu64, val);
> +    setenv(var, val_str, 1);
> +}
> +
> +static void unsetenv_ulong(const char *prefix, const char *name)
> +{
> +    char var[80];
> +    snprintf(var, sizeof(var), "%s%s", prefix, name);
> +    unsetenv(var);
> +}
> +
> +bool getenv_ram(const char *name, void **addrp, size_t *lenp)
> +{
> +    bool found1, found2;
> +    *addrp = (void *) getenv_ulong(ADDR_PREFIX, name, &found1);
> +    *lenp = getenv_ulong(LEN_PREFIX, name, &found2);
> +    assert(found1 == found2);
> +    return found1;
> +}
> +
> +void setenv_ram(const char *name, void *addr, size_t len)
> +{
> +    setenv_ulong(ADDR_PREFIX, name, (uint64_t)addr);
> +    setenv_ulong(LEN_PREFIX, name, len);
> +}
> +
> +void unsetenv_ram(const char *name)
> +{
> +    unsetenv_ulong(ADDR_PREFIX, name);
> +    unsetenv_ulong(LEN_PREFIX, name);
> +}
> +
> +int getenv_fd(const char *name)
> +{
> +    bool found;
> +    int fd = getenv_ulong(FD_PREFIX, name, &found);
> +    if (!found) {
> +        fd = -1;
> +    }
> +    return fd;
> +}
> +
> +void setenv_fd(const char *name, int fd)
> +{
> +    setenv_ulong(FD_PREFIX, name, fd);
> +}
> +
> +void unsetenv_fd(const char *name)
> +{
> +    unsetenv_ulong(FD_PREFIX, name);
> +}
> +
> +bool getenv_bool(const char *name)
> +{
> +    bool found;
> +    bool val = getenv_ulong(BOOL_PREFIX, name, &found);
> +    if (!found) {
> +        val = -1;
> +    }
> +    return val;
> +}
> +
> +void setenv_bool(const char *name, bool val)
> +{
> +    setenv_ulong(BOOL_PREFIX, name, val);
> +}
> +
> +void unsetenv_bool(const char *name)
> +{
> +    unsetenv_ulong(BOOL_PREFIX, name);
> +}
> +
> +int walkenv(const char *prefix, walkenv_cb cb, void *handle)
> +{
> +    char *str, name[128];
> +    char **envp = environ;
> +    size_t prefix_len = strlen(prefix);
> +
> +    while (*envp) {
> +        str = *envp++;
> +        if (!strncmp(str, prefix, prefix_len)) {
> +            char *val = strchr(str, '=');
> +            str += prefix_len;
> +            strncpy(name, str, val - str);
> +            name[val - str] = 0;
> +            if (cb(name, val + 1, handle)) {
> +                return 1;
> +            }
> +        }
> +    }
> +    return 0;
> +}
> +
> +void printenv(void)
> +{
> +    char **ptr = environ;
> +    while (*ptr) {
> +        puts(*ptr++);
> +    }
> +}
> -- 
> 1.8.3.1
> 
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK