* [Qemu-devel] [PATCH] linux-user: added fake open() for /proc/self/cmdline @ 2014-06-17 3:16 lists 2014-06-17 3:16 ` lists 0 siblings, 1 reply; 6+ messages in thread From: lists @ 2014-06-17 3:16 UTC (permalink / raw) To: qemu-devel; +Cc: alex.bennee A piece of software I use depends on /proc/self/cmdline to determine the command with which it was invoked. When using linux-user, that file would read: $ hd /proc/self/cmdline 00000000 2f 75 73 72 2f 62 69 6e 2f 71 65 6d 75 2d 61 72 |/usr/bin/qemu-ar| 00000010 6d 2d 73 74 61 74 69 63 00 2f 75 73 72 2f 62 69 |m-static./usr/bi| 00000020 6e 2f 68 64 00 2f 70 72 6f 63 2f 73 65 6c 66 2f |n/hd./proc/self/| 00000030 63 6d 64 6c 69 6e 65 00 |cmdline.| With this patch, the first word is omitted from the process's own cmdline entry, removing the emulator path from the file: $ hd /proc/self/cmdline 00000000 2f 75 73 72 2f 62 69 6e 2f 68 64 00 2f 70 72 6f |/usr/bin/hd./pro| 00000010 63 2f 73 65 6c 66 2f 63 6d 64 6c 69 6e 65 00 |c/self/cmdline.| 0000001f Kind regards, Wim ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Qemu-devel] [PATCH] linux-user: added fake open() for /proc/self/cmdline 2014-06-17 3:16 [Qemu-devel] [PATCH] linux-user: added fake open() for /proc/self/cmdline lists @ 2014-06-17 3:16 ` lists 2014-06-17 21:09 ` Eric Blake 0 siblings, 1 reply; 6+ messages in thread From: lists @ 2014-06-17 3:16 UTC (permalink / raw) To: qemu-devel; +Cc: Wim Vander Schelden, alex.bennee From: Wim Vander Schelden <wim@fixnum.org> --- linux-user/syscall.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+) diff --git a/linux-user/syscall.c b/linux-user/syscall.c index c134c32..f9fed3e 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -4947,6 +4947,54 @@ int host_to_target_waitstatus(int status) return status; } +static int open_self_cmdline(void *cpu_env, int fd) +{ + int fd_orig = -1; + bool word_skipped = false; + + fd_orig = open("/proc/self/cmdline", O_RDONLY); + if(fd_orig < 0) { + return fd_orig; + } + + while(true) { + ssize_t nb_read; + char buf[128]; + char* cp_buf = buf; + + nb_read = read(fd_orig, buf, sizeof(buf)); + if(nb_read < 0) + { + fd_orig = close(fd_orig); + return -1; + } else if(nb_read == 0) { + break; + } + + if(nb_read == 0) + break; + + if(! word_skipped) { + // Skip the first string, which is the path to qemu-*-static instead of the actual command. + size_t command_length = strnlen(buf, sizeof(buf)); + if(command_length != sizeof(buf)) { + // Null byte found, skip one string + nb_read -= command_length + 1; + cp_buf += command_length + 1; + word_skipped = true; + } + } + + if(word_skipped) { + if(write(fd, cp_buf, nb_read) != nb_read) { + return -1; + } + } + } + + return close(fd_orig); +} + static int open_self_maps(void *cpu_env, int fd) { #if defined(TARGET_ARM) || defined(TARGET_M68K) || defined(TARGET_UNICORE32) @@ -5148,6 +5196,7 @@ static int do_open(void *cpu_env, const char *pathname, int flags, mode_t mode) { "maps", open_self_maps, is_proc_myself }, { "stat", open_self_stat, is_proc_myself }, { "auxv", open_self_auxv, is_proc_myself }, + { "cmdline", open_self_cmdline, is_proc_myself}, #if defined(HOST_WORDS_BIGENDIAN) != defined(TARGET_WORDS_BIGENDIAN) { "/proc/net/route", open_net_route, is_proc }, #endif -- 1.9.1 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [Qemu-devel] [PATCH] linux-user: added fake open() for /proc/self/cmdline 2014-06-17 3:16 ` lists @ 2014-06-17 21:09 ` Eric Blake 2014-06-18 9:02 ` lists 0 siblings, 1 reply; 6+ messages in thread From: Eric Blake @ 2014-06-17 21:09 UTC (permalink / raw) To: lists, qemu-devel; +Cc: Wim Vander Schelden, alex.bennee [-- Attachment #1: Type: text/plain, Size: 2257 bytes --] On 06/16/2014 09:16 PM, lists@fixnum.org wrote: > From: Wim Vander Schelden <wim@fixnum.org> > > --- Missing a Signed-off-by declaration; without that legal hurdle, we are unwilling to take the patch. For more details: http://wiki.qemu.org/Contribute/SubmitAPatch > linux-user/syscall.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 49 insertions(+) Run your patch through scripts/checkpatch.pl to flag many of the complaints below. > > diff --git a/linux-user/syscall.c b/linux-user/syscall.c > index c134c32..f9fed3e 100644 > --- a/linux-user/syscall.c > +++ b/linux-user/syscall.c > @@ -4947,6 +4947,54 @@ int host_to_target_waitstatus(int status) > return status; > } > > +static int open_self_cmdline(void *cpu_env, int fd) > +{ > + int fd_orig = -1; > + bool word_skipped = false; > + > + fd_orig = open("/proc/self/cmdline", O_RDONLY); Why a double space? > + if(fd_orig < 0) { Wrong style - we use space after 'if' > + return fd_orig; > + } > + > + while(true) { and space after 'while' > + if(! word_skipped) { > + // Skip the first string, which is the path to qemu-*-static instead of the actual command. /* */ comments instead of //; fit 80 columns. > + size_t command_length = strnlen(buf, sizeof(buf)); > + if(command_length != sizeof(buf)) { > + // Null byte found, skip one string > + nb_read -= command_length + 1; > + cp_buf += command_length + 1; > + word_skipped = true; This feels a bit complicated. Why not just use memchr() to locate the first NUL byte, rather than messing with strnlen()? > @@ -5148,6 +5196,7 @@ static int do_open(void *cpu_env, const char *pathname, int flags, mode_t mode) > { "maps", open_self_maps, is_proc_myself }, > { "stat", open_self_stat, is_proc_myself }, > { "auxv", open_self_auxv, is_proc_myself }, > + { "cmdline", open_self_cmdline, is_proc_myself}, Match the style of the lines nearby (space before '}') -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org [-- Attachment #2: OpenPGP digital signature --] [-- Type: application/pgp-signature, Size: 604 bytes --] ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [Qemu-devel] [PATCH] linux-user: added fake open() for /proc/self/cmdline 2014-06-17 21:09 ` Eric Blake @ 2014-06-18 9:02 ` lists 2014-06-18 9:02 ` lists 0 siblings, 1 reply; 6+ messages in thread From: lists @ 2014-06-18 9:02 UTC (permalink / raw) To: qemu-devel; +Cc: alex.bennee Hi Eric, Thanks for your feedback. I've addressed the issues you mentioned and verified the patch with checkpatch.pl. The updated patch follows. Kind regards, Wim ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Qemu-devel] [PATCH] linux-user: added fake open() for /proc/self/cmdline 2014-06-18 9:02 ` lists @ 2014-06-18 9:02 ` lists 2014-06-20 12:37 ` Riku Voipio 0 siblings, 1 reply; 6+ messages in thread From: lists @ 2014-06-18 9:02 UTC (permalink / raw) To: qemu-devel; +Cc: alex.bennee, Wim Vander Schelden From: Wim Vander Schelden <wim@fixnum.org> Signed-off-by: Wim Vander Schelden <wim@fixnum.org> --- linux-user/syscall.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) diff --git a/linux-user/syscall.c b/linux-user/syscall.c index c134c32..1be0f09 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -4947,6 +4947,51 @@ int host_to_target_waitstatus(int status) return status; } +static int open_self_cmdline(void *cpu_env, int fd) +{ + int fd_orig = -1; + bool word_skipped = false; + + fd_orig = open("/proc/self/cmdline", O_RDONLY); + if (fd_orig < 0) { + return fd_orig; + } + + while (true) { + ssize_t nb_read; + char buf[128]; + char *cp_buf = buf; + + nb_read = read(fd_orig, buf, sizeof(buf)); + if (nb_read < 0) { + fd_orig = close(fd_orig); + return -1; + } else if (nb_read == 0) { + break; + } + + if (!word_skipped) { + /* Skip the first string, which is the path to qemu-*-static + instead of the actual command. */ + cp_buf = memchr(buf, 0, sizeof(buf)); + if (cp_buf) { + /* Null byte found, skip one string */ + cp_buf++; + nb_read -= cp_buf - buf; + word_skipped = true; + } + } + + if (word_skipped) { + if (write(fd, cp_buf, nb_read) != nb_read) { + return -1; + } + } + } + + return close(fd_orig); +} + static int open_self_maps(void *cpu_env, int fd) { #if defined(TARGET_ARM) || defined(TARGET_M68K) || defined(TARGET_UNICORE32) @@ -5148,6 +5193,7 @@ static int do_open(void *cpu_env, const char *pathname, int flags, mode_t mode) { "maps", open_self_maps, is_proc_myself }, { "stat", open_self_stat, is_proc_myself }, { "auxv", open_self_auxv, is_proc_myself }, + { "cmdline", open_self_cmdline, is_proc_myself }, #if defined(HOST_WORDS_BIGENDIAN) != defined(TARGET_WORDS_BIGENDIAN) { "/proc/net/route", open_net_route, is_proc }, #endif -- 1.9.1 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [Qemu-devel] [PATCH] linux-user: added fake open() for /proc/self/cmdline 2014-06-18 9:02 ` lists @ 2014-06-20 12:37 ` Riku Voipio 0 siblings, 0 replies; 6+ messages in thread From: Riku Voipio @ 2014-06-20 12:37 UTC (permalink / raw) To: lists; +Cc: Wim Vander Schelden, alex.bennee, qemu-devel On Wed, Jun 18, 2014 at 11:02:39AM +0200, lists@fixnum.org wrote: > From: Wim Vander Schelden <wim@fixnum.org> Seems to work, applied to linux-user updates > Signed-off-by: Wim Vander Schelden <wim@fixnum.org> > --- > linux-user/syscall.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 46 insertions(+) > > diff --git a/linux-user/syscall.c b/linux-user/syscall.c > index c134c32..1be0f09 100644 > --- a/linux-user/syscall.c > +++ b/linux-user/syscall.c > @@ -4947,6 +4947,51 @@ int host_to_target_waitstatus(int status) > return status; > } > > +static int open_self_cmdline(void *cpu_env, int fd) > +{ > + int fd_orig = -1; > + bool word_skipped = false; > + > + fd_orig = open("/proc/self/cmdline", O_RDONLY); > + if (fd_orig < 0) { > + return fd_orig; > + } > + > + while (true) { > + ssize_t nb_read; > + char buf[128]; > + char *cp_buf = buf; > + > + nb_read = read(fd_orig, buf, sizeof(buf)); > + if (nb_read < 0) { > + fd_orig = close(fd_orig); > + return -1; > + } else if (nb_read == 0) { > + break; > + } > + > + if (!word_skipped) { > + /* Skip the first string, which is the path to qemu-*-static > + instead of the actual command. */ > + cp_buf = memchr(buf, 0, sizeof(buf)); > + if (cp_buf) { > + /* Null byte found, skip one string */ > + cp_buf++; > + nb_read -= cp_buf - buf; > + word_skipped = true; > + } > + } > + > + if (word_skipped) { > + if (write(fd, cp_buf, nb_read) != nb_read) { > + return -1; > + } > + } > + } > + > + return close(fd_orig); > +} > + > static int open_self_maps(void *cpu_env, int fd) > { > #if defined(TARGET_ARM) || defined(TARGET_M68K) || defined(TARGET_UNICORE32) > @@ -5148,6 +5193,7 @@ static int do_open(void *cpu_env, const char *pathname, int flags, mode_t mode) > { "maps", open_self_maps, is_proc_myself }, > { "stat", open_self_stat, is_proc_myself }, > { "auxv", open_self_auxv, is_proc_myself }, > + { "cmdline", open_self_cmdline, is_proc_myself }, > #if defined(HOST_WORDS_BIGENDIAN) != defined(TARGET_WORDS_BIGENDIAN) > { "/proc/net/route", open_net_route, is_proc }, > #endif > -- > 1.9.1 > ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2014-06-20 12:38 UTC | newest] Thread overview: 6+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2014-06-17 3:16 [Qemu-devel] [PATCH] linux-user: added fake open() for /proc/self/cmdline lists 2014-06-17 3:16 ` lists 2014-06-17 21:09 ` Eric Blake 2014-06-18 9:02 ` lists 2014-06-18 9:02 ` lists 2014-06-20 12:37 ` Riku Voipio
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