From 3bc4181fde899e02aff89f7c0a47f18d37311cb3 Mon Sep 17 00:00:00 2001 From: Clemens Buchacher Date: Wed, 27 Jul 2011 23:32:34 +0200 Subject: [PATCH 1/2] error_routine: use parent's stderr if exec fails The new process's error output may be redirected elsewhere, but if the exec fails, output should still go to the parent's stderr. This has already been done for the die_routine. Do the same for error_routine. Signed-off-by: Clemens Buchacher Signed-off-by: Junio C Hamano --- git-compat-util.h | 2 ++ run-command.c | 15 +++++++-------- usage.c | 18 ++++++++++++++++++ 3 files changed, 27 insertions(+), 8 deletions(-) diff --git a/git-compat-util.h b/git-compat-util.h index e0bb81ed8d..041cbdb93e 100644 --- a/git-compat-util.h +++ b/git-compat-util.h @@ -236,6 +236,7 @@ extern char *gitbasename(char *); /* General helper functions */ extern void vreportf(const char *prefix, const char *err, va_list params); +extern void vwritef(int fd, const char *prefix, const char *err, va_list params); extern NORETURN void usage(const char *err); extern NORETURN void usagef(const char *err, ...) __attribute__((format (printf, 1, 2))); extern NORETURN void die(const char *err, ...) __attribute__((format (printf, 1, 2))); @@ -244,6 +245,7 @@ extern int error(const char *err, ...) __attribute__((format (printf, 1, 2))); extern void warning(const char *err, ...) __attribute__((format (printf, 1, 2))); extern void set_die_routine(NORETURN_PTR void (*routine)(const char *err, va_list params)); +extern void set_error_routine(void (*routine)(const char *err, va_list params)); extern int prefixcmp(const char *str, const char *prefix); extern int suffixcmp(const char *str, const char *suffix); diff --git a/run-command.c b/run-command.c index 70e8a249d0..5c91f37fb8 100644 --- a/run-command.c +++ b/run-command.c @@ -77,16 +77,14 @@ static void notify_parent(void) static NORETURN void die_child(const char *err, va_list params) { - char msg[4096]; - int len = vsnprintf(msg, sizeof(msg), err, params); - if (len > sizeof(msg)) - len = sizeof(msg); - - write_in_full(child_err, "fatal: ", 7); - write_in_full(child_err, msg, len); - write_in_full(child_err, "\n", 1); + vwritef(child_err, "fatal: ", err, params); exit(128); } + +static void error_child(const char *err, va_list params) +{ + vwritef(child_err, "error: ", err, params); +} #endif static inline void set_cloexec(int fd) @@ -217,6 +215,7 @@ fail_pipe: set_cloexec(child_err); } set_die_routine(die_child); + set_error_routine(error_child); close(notify_pipe[0]); set_cloexec(notify_pipe[1]); diff --git a/usage.c b/usage.c index b5e67e3d0d..a2a6678004 100644 --- a/usage.c +++ b/usage.c @@ -4,6 +4,7 @@ * Copyright (C) Linus Torvalds, 2005 */ #include "git-compat-util.h" +#include "cache.h" void vreportf(const char *prefix, const char *err, va_list params) { @@ -12,6 +13,18 @@ void vreportf(const char *prefix, const char *err, va_list params) fprintf(stderr, "%s%s\n", prefix, msg); } +void vwritef(int fd, const char *prefix, const char *err, va_list params) +{ + char msg[4096]; + int len = vsnprintf(msg, sizeof(msg), err, params); + if (len > sizeof(msg)) + len = sizeof(msg); + + write_in_full(fd, prefix, strlen(prefix)); + write_in_full(fd, msg, len); + write_in_full(fd, "\n", 1); +} + static NORETURN void usage_builtin(const char *err, va_list params) { vreportf("usage: ", err, params); @@ -46,6 +59,11 @@ void set_die_routine(NORETURN_PTR void (*routine)(const char *err, va_list param die_routine = routine; } +void set_error_routine(void (*routine)(const char *err, va_list params)) +{ + error_routine = routine; +} + void NORETURN usagef(const char *err, ...) { va_list params; From fc1b56f054a79400c4e72cb1aab97ba2605cbd83 Mon Sep 17 00:00:00 2001 From: Clemens Buchacher Date: Mon, 1 Aug 2011 19:59:21 +0200 Subject: [PATCH 2/2] notice error exit from pager If the pager fails to run, git produces no output, e.g.: $ GIT_PAGER=not-a-command git log The error reporting fails for two reasons: (1) start_command: There is a mechanism that detects errors during execvp introduced in 2b541bf8 (start_command: detect execvp failures early). The child writes one byte to a pipe only if execvp fails. The parent waits for either EOF, when the successful execvp automatically closes the pipe (see FD_CLOEXEC in fcntl(1)), or it reads a single byte, in which case it knows that the execvp failed. This mechanism is incompatible with the workaround introduced in 35ce8622 (pager: Work around window resizing bug in 'less'), which waits for input from the parent before the exec. Since both the parent and the child are waiting for input from each other, that would result in a deadlock. In order to avoid that, the mechanism is disabled by closing the child_notifier file descriptor. (2) finish_command: The parent correctly detects the 127 exit status from the child, but the error output goes nowhere, since by that time it is already being redirected to the child. No simple solution for (1) comes to mind. Number (2) can be solved by not sending error output to the pager. Not redirecting error output to the pager can result in the pager overwriting error output with standard output, however. Since there is no reliable way to handle error reporting in the parent, produce the output in the child instead. Signed-off-by: Clemens Buchacher Signed-off-by: Junio C Hamano --- run-command.c | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-) diff --git a/run-command.c b/run-command.c index 5c91f37fb8..a2796c4cae 100644 --- a/run-command.c +++ b/run-command.c @@ -125,9 +125,6 @@ static int wait_or_whine(pid_t pid, const char *argv0, int silent_exec_failure) if (code == 127) { code = -1; failed_errno = ENOENT; - if (!silent_exec_failure) - error("cannot run %s: %s", argv0, - strerror(ENOENT)); } } else { error("waitpid is confused (%s)", argv0); @@ -282,14 +279,14 @@ fail_pipe: } else { execvp(cmd->argv[0], (char *const*) cmd->argv); } - /* - * Do not check for cmd->silent_exec_failure; the parent - * process will check it when it sees this exit code. - */ - if (errno == ENOENT) + if (errno == ENOENT) { + if (!cmd->silent_exec_failure) + error("cannot run %s: %s", cmd->argv[0], + strerror(ENOENT)); exit(127); - else + } else { die_errno("cannot exec '%s'", cmd->argv[0]); + } } if (cmd->pid < 0) error("cannot fork() for %s: %s", cmd->argv[0],