From: Andre Przywara <andre.przywara@arm.com> To: will.deacon@arm.com, kvm@vger.kernel.org Cc: marc.zyngier@arm.com, kvmarm@lists.cs.columbia.edu, kvm-ppc@vger.kernel.org Subject: [PATCH 10/14] provide generic read_file() implementation Date: Thu, 30 Jul 2015 11:52:27 +0100 [thread overview] Message-ID: <1438253551-2378-11-git-send-email-andre.przywara@arm.com> (raw) In-Reply-To: <1438253551-2378-1-git-send-email-andre.przywara@arm.com> In various parts of kvmtool we simply try to read files into memory, but fail to do so in a safe way. The read(2) syscall can return early having only parts of the file read, or it may return -1 due to being interrupted by a signal (in which case we should simply retry). The ARM code seems to provide the only safe implementation, so take that as an inspiration to provide a generic read_file() function usable by every part of kvmtool. Signed-off-by: Andre Przywara <andre.przywara@arm.com> --- include/kvm/read-write.h | 2 ++ util/read-write.c | 21 +++++++++++++++++++++ 2 files changed, 23 insertions(+) diff --git a/include/kvm/read-write.h b/include/kvm/read-write.h index 87eb167..658a653 100644 --- a/include/kvm/read-write.h +++ b/include/kvm/read-write.h @@ -12,6 +12,8 @@ ssize_t xread(int fd, void *buf, size_t count); ssize_t xwrite(int fd, const void *buf, size_t count); +ssize_t read_file(int fd, char *buf, size_t max_size); + ssize_t read_in_full(int fd, void *buf, size_t count); ssize_t write_in_full(int fd, const void *buf, size_t count); diff --git a/util/read-write.c b/util/read-write.c index 401afd3..32691a9 100644 --- a/util/read-write.c +++ b/util/read-write.c @@ -32,6 +32,27 @@ restart: return nr; } +/* + * Read in the whole file while not exceeding max_size bytes of the buffer. + * Returns -1 (with errno set) in case of an error (ENOMEM if buffer was + * too small) or the filesize if the whole file could be read. + */ +ssize_t read_file(int fd, char *buf, size_t max_size) +{ + ssize_t ret; + char dummy; + + errno = 0; + ret = read_in_full(fd, buf, max_size); + + /* Probe whether we reached EOF. */ + if (xread(fd, &dummy, 1) == 0) + return ret; + + errno = ENOMEM; + return -1; +} + ssize_t read_in_full(int fd, void *buf, size_t count) { ssize_t total = 0; -- 2.3.5
WARNING: multiple messages have this Message-ID (diff)
From: Andre Przywara <andre.przywara@arm.com> To: will.deacon@arm.com, kvm@vger.kernel.org Cc: marc.zyngier@arm.com, kvmarm@lists.cs.columbia.edu, kvm-ppc@vger.kernel.org Subject: [PATCH 10/14] provide generic read_file() implementation Date: Thu, 30 Jul 2015 10:52:27 +0000 [thread overview] Message-ID: <1438253551-2378-11-git-send-email-andre.przywara@arm.com> (raw) In-Reply-To: <1438253551-2378-1-git-send-email-andre.przywara@arm.com> In various parts of kvmtool we simply try to read files into memory, but fail to do so in a safe way. The read(2) syscall can return early having only parts of the file read, or it may return -1 due to being interrupted by a signal (in which case we should simply retry). The ARM code seems to provide the only safe implementation, so take that as an inspiration to provide a generic read_file() function usable by every part of kvmtool. Signed-off-by: Andre Przywara <andre.przywara@arm.com> --- include/kvm/read-write.h | 2 ++ util/read-write.c | 21 +++++++++++++++++++++ 2 files changed, 23 insertions(+) diff --git a/include/kvm/read-write.h b/include/kvm/read-write.h index 87eb167..658a653 100644 --- a/include/kvm/read-write.h +++ b/include/kvm/read-write.h @@ -12,6 +12,8 @@ ssize_t xread(int fd, void *buf, size_t count); ssize_t xwrite(int fd, const void *buf, size_t count); +ssize_t read_file(int fd, char *buf, size_t max_size); + ssize_t read_in_full(int fd, void *buf, size_t count); ssize_t write_in_full(int fd, const void *buf, size_t count); diff --git a/util/read-write.c b/util/read-write.c index 401afd3..32691a9 100644 --- a/util/read-write.c +++ b/util/read-write.c @@ -32,6 +32,27 @@ restart: return nr; } +/* + * Read in the whole file while not exceeding max_size bytes of the buffer. + * Returns -1 (with errno set) in case of an error (ENOMEM if buffer was + * too small) or the filesize if the whole file could be read. + */ +ssize_t read_file(int fd, char *buf, size_t max_size) +{ + ssize_t ret; + char dummy; + + errno = 0; + ret = read_in_full(fd, buf, max_size); + + /* Probe whether we reached EOF. */ + if (xread(fd, &dummy, 1) = 0) + return ret; + + errno = ENOMEM; + return -1; +} + ssize_t read_in_full(int fd, void *buf, size_t count) { ssize_t total = 0; -- 2.3.5
next prev parent reply other threads:[~2015-07-30 10:52 UTC|newest] Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-07-30 10:52 [PATCH 00/14] kvmtool: Refactor kernel image loading to allow pipes Andre Przywara 2015-07-30 10:52 ` Andre Przywara 2015-07-30 10:52 ` [PATCH 01/14] Refactor kernel image loading Andre Przywara 2015-07-30 10:52 ` Andre Przywara 2015-07-30 10:52 ` [PATCH 02/14] arm/powerpc: remove unneeded seeks in kernel loading Andre Przywara 2015-07-30 10:52 ` Andre Przywara 2015-07-30 10:52 ` [PATCH 03/14] x86: allow pipes for bzImage kernel images Andre Przywara 2015-07-30 10:52 ` Andre Przywara 2015-07-30 10:52 ` [PATCH 04/14] x86: support loading flat binary kernel images from a pipe Andre Przywara 2015-07-30 10:52 ` Andre Przywara 2015-07-30 10:52 ` [PATCH 05/14] kvmtool: introduce pseek Andre Przywara 2015-07-30 10:52 ` Andre Przywara 2015-07-30 10:52 ` [PATCH 06/14] MIPS: use pseek() in ELF kernel image loading Andre Przywara 2015-07-30 10:52 ` Andre Przywara 2015-07-30 10:52 ` [PATCH 07/14] MIPS: move ELF headers loading outside of load_elf_binary() Andre Przywara 2015-07-30 10:52 ` Andre Przywara 2015-07-30 10:52 ` [PATCH 08/14] MIPS: remove seeks from load_flat_binary() Andre Przywara 2015-07-30 10:52 ` Andre Przywara 2015-07-30 10:52 ` [PATCH 09/14] arm: move kernel loading into arm/kvm.c Andre Przywara 2015-07-30 10:52 ` Andre Przywara 2015-07-30 10:52 ` Andre Przywara [this message] 2015-07-30 10:52 ` [PATCH 10/14] provide generic read_file() implementation Andre Przywara 2015-07-30 10:52 ` [PATCH 11/14] arm/arm64: use read_file() in kernel and initrd loading Andre Przywara 2015-07-30 10:52 ` Andre Przywara 2015-07-30 10:52 ` [PATCH 12/14] powerpc: " Andre Przywara 2015-07-30 10:52 ` Andre Przywara 2015-07-30 10:52 ` [PATCH 13/14] MIPS: use read wrappers in kernel loading Andre Przywara 2015-07-30 10:52 ` Andre Przywara 2015-07-30 10:52 ` [PATCH 14/14] x86: " Andre Przywara 2015-07-30 10:52 ` Andre Przywara
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