git-daemon regression: 650c449250d7 common-main: call git_extract_argv0_path()

Greetings,

git-daemon went broke on me post v2.9.3 due to binaries being installed in /usr/lib/git, which is not in PATH. Reverting 650c449250d7 fixes it up, as does ln -s /usr/lib/git/git-daemon /usr/bin/git-daemon 'course, but thought I should report it, since it used to work without that.

Process 18804 attached restart_syscall(<... resuming interrupted call ...>) = 1 accept(4, {sa_family=AF_INET6, sin6_port=htons(44400), inet_pton(AF_INET6, "::1", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, [28]) = 5 dup(5) = 6 pipe([7, 8]) = 0 clone(Process 18830 attached child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7f0e6061c9d0) = 18830 [pid 18830] set_robust_list(0x7f0e6061c9e0, 24 <unfinished ...> [pid 18804] close(8 <unfinished ...> [pid 18830] <... set_robust_list resumed> ) = 0 [pid 18804] <... close resumed> ) = 0 [pid 18804] read(7, <unfinished ...> [pid 18830] close(7) = 0 [pid 18830] fcntl(8, F_GETFD) = 0 [pid 18830] fcntl(8, F_SETFD, FD_CLOEXEC) = 0 [pid 18830] dup2(5, 0) = 0 [pid 18830] close(5) = 0 [pid 18830] dup2(6, 1) = 1 [pid 18830] close(6) = 0 [pid 18830] execve("/usr/local/sbin/git-daemon", ["git-daemon", "--serve", "--syslog", "--detach", "--reuseaddr", "--user=git", "--group=daemon", "--pid-file=/var/run/git-daemon.p"..., "--export-all", "--user-path"], ["CONSOLE=/dev/console", "LC_ALL=POSIX", "REDIRECT=/dev/tty7", "COLUMNS=320", "PATH=/usr/local/sbin:/usr/local/"..., "PWD=/", "LINES=90", "SHLVL=1", "LC_CTYPE=en_US.UTF-8", "_=/sbin/startproc", "PREVLEVEL=", "RUNLEVEL=5", "DAEMON=/usr/lib/git/git-daemon", "REMOTE_ADDR=[::1]", "REMOTE_PORT=44400"]) = -1 ENOENT (No such file or directory) [pid 18830] execve("/usr/local/bin/git-daemon", ["git-daemon", "--serve", "--syslog", "--detach", "--reuseaddr", "--user=git", "--group=daemon", "--pid-file=/var/run/git-daemon.p"..., "--export-all", "--user-path"], ["CONSOLE=/dev/console", "LC_ALL=POSIX", "REDIRECT=/dev/tty7", "COLUMNS=320", "PATH=/usr/local/sbin:/usr/local/"..., "PWD=/", "LINES=90", "SHLVL=1", "LC_CTYPE=en_US.UTF-8", "_=/sbin/startproc", "PREVLEVEL=", "RUNLEVEL=5", "DAEMON=/usr/lib/git/git-daemon", "REMOTE_ADDR=[::1]", "REMOTE_PORT=44400"]) = -1 ENOENT (No such file or directory) [pid 18830] execve("/usr/sbin/git-daemon", ["git-daemon", "--serve", "--syslog", "--detach", "--reuseaddr", "--user=git", "--group=daemon", "--pid-file=/var/run/git-daemon.p"..., "--export-all", "--user-path"], ["CONSOLE=/dev/console", "LC_ALL=POSIX", "REDIRECT=/dev/tty7", "COLUMNS=320", "PATH=/usr/local/sbin:/usr/local/"..., "PWD=/", "LINES=90", "SHLVL=1", "LC_CTYPE=en_US.UTF-8", "_=/sbin/startproc", "PREVLEVEL=", "RUNLEVEL=5", "DAEMON=/usr/lib/git/git-daemon", "REMOTE_ADDR=[::1]", "REMOTE_PORT=44400"]) = -1 ENOENT (No such file or directory) [pid 18830] execve("/usr/bin/git-daemon", ["git-daemon", "--serve", "--syslog", "--detach", "--reuseaddr", "--user=git", "--group=daemon", "--pid-file=/var/run/git-daemon.p"..., "--export-all", "--user-path"], ["CONSOLE=/dev/console", "LC_ALL=POSIX", "REDIRECT=/dev/tty7", "COLUMNS=320", "PATH=/usr/local/sbin:/usr/local/"..., "PWD=/", "LINES=90", "SHLVL=1", "LC_CTYPE=en_US.UTF-8", "_=/sbin/startproc", "PREVLEVEL=", "RUNLEVEL=5", "DAEMON=/usr/lib/git/git-daemon", "REMOTE_ADDR=[::1]", "REMOTE_PORT=44400"]) = -1 ENOENT (No such file or directory) [pid 18830] execve("/sbin/git-daemon", ["git-daemon", "--serve", "--syslog", "--detach", "--reuseaddr", "--user=git", "--group=daemon", "--pid-file=/var/run/git-daemon.p"..., "--export-all", "--user-path"], ["CONSOLE=/dev/console", "LC_ALL=POSIX", "REDIRECT=/dev/tty7", "COLUMNS=320", "PATH=/usr/local/sbin:/usr/local/"..., "PWD=/", "LINES=90", "SHLVL=1", "LC_CTYPE=en_US.UTF-8", "_=/sbin/startproc", "PREVLEVEL=", "RUNLEVEL=5", "DAEMON=/usr/lib/git/git-daemon", "REMOTE_ADDR=[::1]", "REMOTE_PORT=44400"]) = -1 ENOENT (No such file or directory) [pid 18830] execve("/bin/git-daemon", ["git-daemon", "--serve", "--syslog", "--detach", "--reuseaddr", "--user=git", "--group=daemon", "--pid-file=/var/run/git-daemon.p"..., "--export-all", "--user-path"], ["CONSOLE=/dev/console", "LC_ALL=POSIX", "REDIRECT=/dev/tty7", "COLUMNS=320", "PATH=/usr/local/sbin:/usr/local/"..., "PWD=/", "LINES=90", "SHLVL=1", "LC_CTYPE=en_US.UTF-8", "_=/sbin/startproc", "PREVLEVEL=", "RUNLEVEL=5", "DAEMON=/usr/lib/git/git-daemon", "REMOTE_ADDR=[::1]", "REMOTE_PORT=44400"]) = -1 ENOENT (No such file or directory) [pid 18830] fstat(2, {st_dev=makedev(0, 6), st_ino=1029, st_mode=S_IFCHR|0666, st_nlink=1, st_uid=0, st_gid=0, st_blksize=4096, st_blocks=0, st_rdev=makedev(1, 3), st_atime=2016/11/26-00:42:47, st_mtime=2016/11/26-00:42:47, st_ctime=2016/11/26-00:42:47}) = 0 [pid 18830] ioctl(2, TCGETS, 0x7ffe6dbd09b0) = -1 ENOTTY (Inappropriate ioctl for device) [pid 18830] mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f0e60632000 [pid 18830] write(2, "error: cannot run git-daemon: No"..., 56) = 56 [pid 18830] write(8, "\0", 1) = 1 [pid 18804] <... read resumed> "\0", 1) = 1 [pid 18830] exit_group(127) = ? [pid 18804] wait4(18830, <unfinished ...> [pid 18830] +++ exited with 127 +++ <... wait4 resumed> [{WIFEXITED(s) && WEXITSTATUS(s) == 127}], 0, NULL) = 18830 --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=18830, si_uid=1002, si_status=127, si_utime=0, si_stime=0} --- rt_sigaction(SIGCHLD, {0x404e10, [CHLD], SA_RESTORER|SA_RESTART, 0x7f0e5f6a7140}, {0x404e10, [CHLD], SA_RESTORER|SA_RESTART, 0x7f0e5f6a7140}, 8) = 0 rt_sigreturn({mask=[]}) = 18830 close(7) = 0 close(5) = 0 close(6) = 0 open("/etc/localtime", O_RDONLY|O_CLOEXEC) = 5 fstat(5, {st_dev=makedev(8, 5), st_ino=6031966, st_mode=S_IFREG|0644, st_nlink=2, st_uid=0, st_gid=0, st_blksize=4096, st_blocks=8, st_size=2335, st_atime=2016/11/26-01:00:02, st_mtime=2016/11/08-18:09:53, st_ctime=2016/11/09-21:15:24}) = 0 fstat(5, {st_dev=makedev(8, 5), st_ino=6031966, st_mode=S_IFREG|0644, st_nlink=2, st_uid=0, st_gid=0, st_blksize=4096, st_blocks=8, st_size=2335, st_atime=2016/11/26-01:00:02, st_mtime=2016/11/08-18:09:53, st_ctime=2016/11/09-21:15:24}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f0e60632000 read(5, "TZif2\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\t\0\0\0\t\0\0\0\0"..., 4096) = 2335 lseek(5, -1476, SEEK_CUR) = 859 read(5, "TZif2\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\t\0\0\0\t\0\0\0\0"..., 4096) = 1476 close(5) = 0 munmap(0x7f0e60632000, 4096) = 0 socket(PF_LOCAL, SOCK_DGRAM|SOCK_CLOEXEC, 0) = 5 connect(5, {sa_family=AF_LOCAL, sun_path="/dev/log"}, 110) = 0 sendto(5, "<27>Nov 26 14:25:55 git-daemon[1"..., 53, MSG_NOSIGNAL, NULL, 0) = 53 poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}], 2, 4294967295

revert 650c449250d7

Process 18934 attached restart_syscall(<... resuming interrupted call ...>) = 1 accept(4, {sa_family=AF_INET6, sin6_port=htons(44404), inet_pton(AF_INET6, "::1", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, [28]) = 5 dup(5) = 6 pipe([7, 8]) = 0 clone(Process 19010 attached child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7f62fcb5e9d0) = 19010 [pid 18934] close(8 <unfinished ...> [pid 19010] set_robust_list(0x7f62fcb5e9e0, 24) = 0 [pid 18934] <... close resumed> ) = 0 [pid 18934] read(7, <unfinished ...> [pid 19010] close(7) = 0 [pid 19010] fcntl(8, F_GETFD) = 0 [pid 19010] fcntl(8, F_SETFD, FD_CLOEXEC) = 0 [pid 19010] dup2(5, 0) = 0 [pid 19010] close(5) = 0 [pid 19010] dup2(6, 1) = 1 [pid 19010] close(6) = 0 [pid 19010] execve("/usr/lib/git/git-daemon", ["/usr/lib/git/git-daemon", "--serve", "--syslog", "--detach", "--reuseaddr", "--user=git", "--group=daemon", "--pid-file=/var/run/git-daemon.p"..., "--export-all", "--user-path"], ["CONSOLE=/dev/console", "LC_ALL=POSIX", "REDIRECT=/dev/tty7", "COLUMNS=320", "PATH=/usr/local/sbin:/usr/local/"..., "PWD=/", "LINES=90", "SHLVL=1", "LC_CTYPE=en_US.UTF-8", "_=/sbin/startproc", "PREVLEVEL=", "RUNLEVEL=5", "DAEMON=/usr/lib/git/git-daemon", "REMOTE_ADDR=[::1]", "REMOTE_PORT=44404"] <unfinished ...> [pid 18934] <... read resumed> "", 1) = 0 [pid 19010] <... execve resumed> ) = 0 .... works

ln -s /usr/lib/git/git-daemon /usr/bin/git-daemon

Process 19862 attached restart_syscall(<... resuming interrupted call ...>) = 1 accept(4, {sa_family=AF_INET6, sin6_port=htons(44412), inet_pton(AF_INET6, "::1", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, [28]) = 5 dup(5) = 6 pipe([7, 8]) = 0 clone(Process 19915 attached child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7fc97962e9d0) = 19915 [pid 19862] close(8) = 0 [pid 19915] set_robust_list(0x7fc97962e9e0, 24 <unfinished ...> [pid 19862] read(7, <unfinished ...> [pid 19915] <... set_robust_list resumed> ) = 0 [pid 19915] close(7) = 0 [pid 19915] fcntl(8, F_GETFD) = 0 [pid 19915] fcntl(8, F_SETFD, FD_CLOEXEC) = 0 [pid 19915] dup2(5, 0) = 0 [pid 19915] close(5) = 0 [pid 19915] dup2(6, 1) = 1 [pid 19915] close(6) = 0 [pid 19915] execve("/usr/local/sbin/git-daemon", ["git-daemon", "--serve", "--syslog", "--detach", "--reuseaddr", "--user=git", "--group=daemon", "--pid-file=/var/run/git-daemon.p"..., "--export-all", "--user-path"], ["CONSOLE=/dev/console", "LC_ALL=POSIX", "REDIRECT=/dev/tty7", "COLUMNS=320", "PATH=/usr/local/sbin:/usr/local/"..., "PWD=/", "LINES=90", "SHLVL=1", "LC_CTYPE=en_US.UTF-8", "_=/sbin/startproc", "PREVLEVEL=", "RUNLEVEL=5", "DAEMON=/usr/lib/git/git-daemon", "REMOTE_ADDR=[::1]", "REMOTE_PORT=44412"]) = -1 ENOENT (No such file or directory) [pid 19915] execve("/usr/local/bin/git-daemon", ["git-daemon", "--serve", "--syslog", "--detach", "--reuseaddr", "--user=git", "--group=daemon", "--pid-file=/var/run/git-daemon.p"..., "--export-all", "--user-path"], ["CONSOLE=/dev/console", "LC_ALL=POSIX", "REDIRECT=/dev/tty7", "COLUMNS=320", "PATH=/usr/local/sbin:/usr/local/"..., "PWD=/", "LINES=90", "SHLVL=1", "LC_CTYPE=en_US.UTF-8", "_=/sbin/startproc", "PREVLEVEL=", "RUNLEVEL=5", "DAEMON=/usr/lib/git/git-daemon", "REMOTE_ADDR=[::1]", "REMOTE_PORT=44412"]) = -1 ENOENT (No such file or directory) [pid 19915] execve("/usr/sbin/git-daemon", ["git-daemon", "--serve", "--syslog", "--detach", "--reuseaddr", "--user=git", "--group=daemon", "--pid-file=/var/run/git-daemon.p"..., "--export-all", "--user-path"], ["CONSOLE=/dev/console", "LC_ALL=POSIX", "REDIRECT=/dev/tty7", "COLUMNS=320", "PATH=/usr/local/sbin:/usr/local/"..., "PWD=/", "LINES=90", "SHLVL=1", "LC_CTYPE=en_US.UTF-8", "_=/sbin/startproc", "PREVLEVEL=", "RUNLEVEL=5", "DAEMON=/usr/lib/git/git-daemon", "REMOTE_ADDR=[::1]", "REMOTE_PORT=44412"]) = -1 ENOENT (No such file or directory) [pid 19915] execve("/usr/bin/git-daemon", ["git-daemon", "--serve", "--syslog", "--detach", "--reuseaddr", "--user=git", "--group=daemon", "--pid-file=/var/run/git-daemon.p"..., "--export-all", "--user-path"], ["CONSOLE=/dev/console", "LC_ALL=POSIX", "REDIRECT=/dev/tty7", "COLUMNS=320", "PATH=/usr/local/sbin:/usr/local/"..., "PWD=/", "LINES=90", "SHLVL=1", "LC_CTYPE=en_US.UTF-8", "_=/sbin/startproc", "PREVLEVEL=", "RUNLEVEL=5", "DAEMON=/usr/lib/git/git-daemon", "REMOTE_ADDR=[::1]", "REMOTE_PORT=44412"] <unfinished ...> [pid 19862] <... read resumed> "", 1) = 0 [pid 19915] <... execve resumed> ) = 0 .... works

Hi Mike,

On Sat, 2016-11-26 at 15:03 +0100, Mike Galbraith wrote:

I don't know how you usually install git, but git-daemon is not supposed to be in $PATH, the correct way to invoke the git daemon is 'git daemon' not 'git-daemon'

Having all subcommands of git as separate binaries in your $PATH is an ancient git.git practice that stopped being used/supported quite a while ago.

I don't know why this patch broke that obsolete practice, but hopefully this can help you forward.

D.

On Sat, Nov 26, 2016 at 03:03:48PM +0100, Mike Galbraith wrote:

Generally /usr/lib/git _should_ be in your PATH, as it is added by the git wrapper when you run "git daemon".

The only behavior difference caused by 650c449250d7 is that we replace argv[0] with the output of git_extract_argv0_path(argv[0]), which will give the basename, not a full path. So presumably you are running:

  /usr/lib/git/git-daemon

directly. I'm not sure that's even supposed to work these days, and it was not just a happy accident that it did.

On the other hand, I am sympathetic that something used to work and now doesn't. It probably wouldn't be that hard to work around it.

The reason for the behavior change is that one of the cmd_main() functions was relying on the basename side-effect of the extract_argv0_path function, so 650c449250d7 just feeds the munged argv[0] to all of the programs. The cleanest fix would probably be something like:

On Sat, 2016-11-26 at 12:09 -0500, Jeff King wrote:

Ah. I'm using suse's rpm glue to package my modified source, and its startup script still calls it directly, so wants some modernization.

That did fix it up, thanks.  I'll try twiddling the script instead.

On Sat, Nov 26, 2016 at 06:51:11PM +0100, Mike Galbraith wrote:

Thanks for confirming. Here it is, with a commit message and a little bit of polish.

-- >8 --
Subject: [PATCH] common-main: stop munging argv[0] path

Since 650c44925 (common-main: call git_extract_argv0_path(), 2016-07-01), the argv[0] that is seen in cmd_main() of individual programs is always the basename of the executable, as common-main strips off the full path. This can produce confusing results for git-daemon, which wants to re-exec itself.

For instance, if the program was originally run as "/usr/lib/git/git-daemon", it will try just re-execing "git-daemon", which will find the first instance in $PATH. If git's exec-path has not been prepended to $PATH, we may find the git-daemon from a different version (or no git-daemon at all).

Normally this isn't a problem. Git commands are run as "git daemon", the git wrapper puts the exec-path at the front of $PATH, and argv[0] is already "daemon" anyway. But running git-daemon via its full exec-path, while not really a recommended method, did work prior to 650c44925. Let's make it work again.

The real goal of 650c44925 was not to munge argv[0], but to reliably set the argv0_path global. The only reason it munges at all is that one caller, the git.c wrapper, piggy-backed on that computation to find the command basename. Instead, let's leave argv[0] untouched in common-main, and have git.c do its own basename computation.

While we're at it, let's drop the return value from git_extract_argv0_path(). It was only ever used in this one callsite, and its dual purposes is what led to this confusion in the first place.

Note that by changing the interface, the compiler can confirm for us that there are no other callers storing the return value. But the compiler can't tell us whether any of the cmd_main() functions (besides git.c) were relying on the basename munging. However, we can observe that prior to 650c44925, no other cmd_main() functions did that munging, and no new cmd_main() functions have been introduced since then. So we can't be regressing any of those cases.

Signed-off-by: Jeff King <peff@peff.net>
---
 common-main.c |  2 +-
 exec_cmd.c    | 10 +++-------
 exec_cmd.h    |  2 +-
 git.c         |  5 +++++
 4 files changed, 10 insertions(+), 9 deletions(-)