Introduce die_errno() that appends strerror(errno) to die()

There are many calls to die() that do, or should, report
strerror(errno) to indicate how the syscall they guard failed.
Introduce a small helper function for this case.

Note:

- POSIX says vsnprintf can modify errno in some unlikely cases, so we
  have to use errno early.

- We take some care to pass the original format to die_routine(), in
  case someone wants to call die_errno() with custom format
  characters.

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/git-compat-util.h b/git-compat-util.h
index f25f7f1a9eda48477485c2406402a0a06fd9c8e3..0366cde05cef3c6323d21e92b4f8596eb6a34a84 100644 (file)
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -162,6 +162,7 @@ extern char *gitbasename(char *);
 /* General helper functions */
 extern void usage(const char *err) NORETURN;
 extern void die(const char *err, ...) NORETURN __attribute__((format (printf, 1, 2)));
+extern void die_errno(const char *err, ...) NORETURN __attribute__((format (printf, 1, 2)));
 extern int error(const char *err, ...) __attribute__((format (printf, 1, 2)));
 extern void warning(const char *err, ...) __attribute__((format (printf, 1, 2)));
 

diff --git a/usage.c b/usage.c
index 820d09f92b03b6cc96fbe9a954c37fd2d5e5a417..fd936a1aebd05df53ef49e79825286a804f4ccd2 100644 (file)
--- a/usage.c
+++ b/usage.c
@@ -60,6 +60,18 @@ void die(const char *err, ...)
        va_end(params);
 }
 
+void die_errno(const char *fmt, ...)
+{
+       va_list params;
+       char fmt_with_err[1024];
+
+       snprintf(fmt_with_err, sizeof(fmt_with_err), "%s: %s", fmt, strerror(errno));
+
+       va_start(params, fmt);
+       die_routine(fmt_with_err, params);
+       va_end(params);
+}
+
 int error(const char *err, ...)
 {
        va_list params;