Git Source Code Mirror - This is a publish-only repository and all pull requests are ignored. Please follow Documentation/SubmittingPatches procedure for any of your improvements. https://git-scm.com/
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
git/write-or-die.c

111 lines
2.3 KiB

#include "cache.h"
#include "config.h"
write_or_die: handle EPIPE in async threads When write_or_die() sees EPIPE, it treats it specially by converting it into a SIGPIPE death. We obviously cannot ignore it, as the write has failed and the caller expects us to die. But likewise, we cannot just call die(), because printing any message at all would be a nuisance during normal operations. However, this is a problem if write_or_die() is called from a thread. Our raised signal ends up killing the whole process, when logically we just need to kill the thread (after all, if we are ignoring SIGPIPE, there is good reason to think that the main thread is expecting to handle it). Inside an async thread, the die() code already does the right thing, because we use our custom die_async() routine, which calls pthread_join(). So ideally we would piggy-back on that, and simply call: die_quietly_with_code(141); or similar. But refactoring the die code to do this is surprisingly non-trivial. The die_routines themselves handle both printing and the decision of the exit code. Every one of them would have to be modified to take new parameters for the code, and to tell us to be quiet. Instead, we can just teach write_or_die() to check for the async case and handle it specially. We do have to build an interface to abstract the async exit, but it's simple and self-contained. If we had many call-sites that wanted to do this die_quietly_with_code(), this approach wouldn't scale as well, but we don't. This is the only place where do this weird exit trick. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
7 years ago
#include "run-command.h"
/*
* Some cases use stdio, but want to flush after the write
* to get error handling (and to get better interactive
* behaviour - not buffering excessively).
*
* Of course, if the flush happened within the write itself,
* we've already lost the error code, and cannot report it any
* more. So we just ignore that case instead (and hope we get
* the right error code on the flush).
*
* If the file handle is stdout, and stdout is a file, then skip the
* flush entirely since it's not needed.
*/
void maybe_flush_or_die(FILE *f, const char *desc)
{
static int skip_stdout_flush = -1;
struct stat st;
char *cp;
if (f == stdout) {
if (skip_stdout_flush < 0) {
cp = getenv("GIT_FLUSH");
if (cp)
skip_stdout_flush = (atoi(cp) == 0);
else if ((fstat(fileno(stdout), &st) == 0) &&
S_ISREG(st.st_mode))
skip_stdout_flush = 1;
else
skip_stdout_flush = 0;
}
if (skip_stdout_flush && !ferror(f))
return;
}
if (fflush(f)) {
write_or_die: raise SIGPIPE when we get EPIPE The write_or_die function will always die on an error, including EPIPE. However, it currently treats EPIPE specially by suppressing any error message, and by exiting with exit code 0. Suppressing the error message makes some sense; a pipe death may just be a sign that the other side is not interested in what we have to say. However, exiting with a successful error code is not a good idea, as write_or_die is frequently used in cases where we want to be careful about having written all of the output, and we may need to signal to our caller that we have done so (e.g., you would not want a push whose other end has hung up to report success). This distinction doesn't typically matter in git, because we do not ignore SIGPIPE in the first place. Which means that we will not get EPIPE, but instead will just die when we get a SIGPIPE. But it's possible for a default handler to be set by a parent process, or for us to add a callsite inside one of our few SIGPIPE-ignoring blocks of code. This patch converts write_or_die to actually raise SIGPIPE when we see EPIPE, rather than exiting with zero. This brings the behavior in line with the "normal" case that we die from SIGPIPE (and any callers who want to check why we died will see the same thing). We also give the same treatment to other related functions, including write_or_whine_pipe and maybe_flush_or_die. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
10 years ago
check_pipe(errno);
die_errno("write failure on '%s'", desc);
}
}
void fprintf_or_die(FILE *f, const char *fmt, ...)
{
va_list ap;
int ret;
va_start(ap, fmt);
ret = vfprintf(f, fmt, ap);
va_end(ap);
if (ret < 0) {
check_pipe(errno);
die_errno("write error");
}
}
static int maybe_fsync(int fd)
{
if (use_fsync < 0)
use_fsync = git_env_bool("GIT_TEST_FSYNC", 1);
if (!use_fsync)
return 0;
if (fsync_method == FSYNC_METHOD_WRITEOUT_ONLY &&
git_fsync(fd, FSYNC_WRITEOUT_ONLY) >= 0)
return 0;
return git_fsync(fd, FSYNC_HARDWARE_FLUSH);
}
void fsync_or_die(int fd, const char *msg)
{
if (maybe_fsync(fd) < 0)
die_errno("fsync error on '%s'", msg);
}
int fsync_component(enum fsync_component component, int fd)
{
if (fsync_components & component)
return maybe_fsync(fd);
return 0;
}
void fsync_component_or_die(enum fsync_component component, int fd, const char *msg)
{
if (fsync_components & component)
fsync_or_die(fd, msg);
}
void write_or_die(int fd, const void *buf, size_t count)
{
if (write_in_full(fd, buf, count) < 0) {
write_or_die: raise SIGPIPE when we get EPIPE The write_or_die function will always die on an error, including EPIPE. However, it currently treats EPIPE specially by suppressing any error message, and by exiting with exit code 0. Suppressing the error message makes some sense; a pipe death may just be a sign that the other side is not interested in what we have to say. However, exiting with a successful error code is not a good idea, as write_or_die is frequently used in cases where we want to be careful about having written all of the output, and we may need to signal to our caller that we have done so (e.g., you would not want a push whose other end has hung up to report success). This distinction doesn't typically matter in git, because we do not ignore SIGPIPE in the first place. Which means that we will not get EPIPE, but instead will just die when we get a SIGPIPE. But it's possible for a default handler to be set by a parent process, or for us to add a callsite inside one of our few SIGPIPE-ignoring blocks of code. This patch converts write_or_die to actually raise SIGPIPE when we see EPIPE, rather than exiting with zero. This brings the behavior in line with the "normal" case that we die from SIGPIPE (and any callers who want to check why we died will see the same thing). We also give the same treatment to other related functions, including write_or_whine_pipe and maybe_flush_or_die. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
10 years ago
check_pipe(errno);
die_errno("write error");
}
}
void fwrite_or_die(FILE *f, const void *buf, size_t count)
{
if (fwrite(buf, 1, count, f) != count)
die_errno("fwrite error");
}
void fflush_or_die(FILE *f)
{
if (fflush(f))
die_errno("fflush error");
}