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authorPaul Tan <pyokagan@gmail.com>2015-08-04 21:51:22 +0800
committerJunio C Hamano <gitster@pobox.com>2015-08-04 22:02:11 -0700
commit3ff53df7b4cbc331d302181d2d6644f4cb860a52 (patch)
treec2525de3b28e7dd2b6a1ede3d867f2d7ed4ac08d /wrapper.c
parentd939af12bd96db7ad3e671a0585ad8570aa7e9d3 (diff)
downloadgit-3ff53df7b4cbc331d302181d2d6644f4cb860a52.tar.gz
wrapper: implement xopen()
A common usage pattern of open() is to check if it was successful, and die() if it was not: int fd = open(path, O_WRONLY | O_CREAT, 0777); if (fd < 0) die_errno(_("Could not open '%s' for writing."), path); Implement a wrapper function xopen() that does the above so that we can save a few lines of code, and make the die() messages consistent. Helped-by: Torsten Bögershausen <tboegi@web.de> Helped-by: Jeff King <peff@peff.net> Helped-by: Johannes Schindelin <johannes.schindelin@gmx.de> Helped-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'wrapper.c')
-rw-r--r--wrapper.c35
1 files changed, 35 insertions, 0 deletions
diff --git a/wrapper.c b/wrapper.c
index ff49807948..0a4502d232 100644
--- a/wrapper.c
+++ b/wrapper.c
@@ -189,6 +189,41 @@ void *xcalloc(size_t nmemb, size_t size)
# endif
#endif
+/**
+ * xopen() is the same as open(), but it die()s if the open() fails.
+ */
+int xopen(const char *path, int oflag, ...)
+{
+ mode_t mode = 0;
+ va_list ap;
+
+ /*
+ * va_arg() will have undefined behavior if the specified type is not
+ * compatible with the argument type. Since integers are promoted to
+ * ints, we fetch the next argument as an int, and then cast it to a
+ * mode_t to avoid undefined behavior.
+ */
+ va_start(ap, oflag);
+ if (oflag & O_CREAT)
+ mode = va_arg(ap, int);
+ va_end(ap);
+
+ for (;;) {
+ int fd = open(path, oflag, mode);
+ if (fd >= 0)
+ return fd;
+ if (errno == EINTR)
+ continue;
+
+ if ((oflag & O_RDWR) == O_RDWR)
+ die_errno(_("could not open '%s' for reading and writing"), path);
+ else if ((oflag & O_WRONLY) == O_WRONLY)
+ die_errno(_("could not open '%s' for writing"), path);
+ else
+ die_errno(_("could not open '%s' for reading"), path);
+ }
+}
+
/*
* xread() is the same a read(), but it automatically restarts read()
* operations with a recoverable error (EAGAIN and EINTR). xread()