path helpers: move git_mkstemp* to wrapper.c

git_mkstemp_mode and related functions do not require access to
specialized git machinery, unlike some other functions from
path.c (like set_shared_perm()).  Move them to wrapper.c where
the wrapper xmkstemp_mode is defined.

This eliminates a dependency of wrapper.o on environment.o via
path.o.  With typical linkers (e.g., gcc), that dependency makes
programs that use functions from wrapper.o and not environment.o
or path.o larger than they need to be.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 113 insertions, 0 deletions

diff --git a/wrapper.c b/wrapper.c
index e67b70a108..b3efefb539 100644
--- a/wrapper.c
+++ b/wrapper.c
@@ -204,6 +204,119 @@ int xmkstemp(char *template)
 	return fd;
 }
 
+/* git_mkstemp() - create tmp file honoring TMPDIR variable */
+int git_mkstemp(char *path, size_t len, const char *template)
+{
+	const char *tmp;
+	size_t n;
+
+	tmp = getenv("TMPDIR");
+	if (!tmp)
+		tmp = "/tmp";
+	n = snprintf(path, len, "%s/%s", tmp, template);
+	if (len <= n) {
+		errno = ENAMETOOLONG;
+		return -1;
+	}
+	return mkstemp(path);
+}
+
+/* git_mkstemps() - create tmp file with suffix honoring TMPDIR variable. */
+int git_mkstemps(char *path, size_t len, const char *template, int suffix_len)
+{
+	const char *tmp;
+	size_t n;
+
+	tmp = getenv("TMPDIR");
+	if (!tmp)
+		tmp = "/tmp";
+	n = snprintf(path, len, "%s/%s", tmp, template);
+	if (len <= n) {
+		errno = ENAMETOOLONG;
+		return -1;
+	}
+	return mkstemps(path, suffix_len);
+}
+
+/* Adapted from libiberty's mkstemp.c. */
+
+#undef TMP_MAX
+#define TMP_MAX 16384
+
+int git_mkstemps_mode(char *pattern, int suffix_len, int mode)
+{
+	static const char letters[] =
+		"abcdefghijklmnopqrstuvwxyz"
+		"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+		"0123456789";
+	static const int num_letters = 62;
+	uint64_t value;
+	struct timeval tv;
+	char *template;
+	size_t len;
+	int fd, count;
+
+	len = strlen(pattern);
+
+	if (len < 6 + suffix_len) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	if (strncmp(&pattern[len - 6 - suffix_len], "XXXXXX", 6)) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	/*
+	 * Replace pattern's XXXXXX characters with randomness.
+	 * Try TMP_MAX different filenames.
+	 */
+	gettimeofday(&tv, NULL);
+	value = ((size_t)(tv.tv_usec << 16)) ^ tv.tv_sec ^ getpid();
+	template = &pattern[len - 6 - suffix_len];
+	for (count = 0; count < TMP_MAX; ++count) {
+		uint64_t v = value;
+		/* Fill in the random bits. */
+		template[0] = letters[v % num_letters]; v /= num_letters;
+		template[1] = letters[v % num_letters]; v /= num_letters;
+		template[2] = letters[v % num_letters]; v /= num_letters;
+		template[3] = letters[v % num_letters]; v /= num_letters;
+		template[4] = letters[v % num_letters]; v /= num_letters;
+		template[5] = letters[v % num_letters]; v /= num_letters;
+
+		fd = open(pattern, O_CREAT | O_EXCL | O_RDWR, mode);
+		if (fd > 0)
+			return fd;
+		/*
+		 * Fatal error (EPERM, ENOSPC etc).
+		 * It doesn't make sense to loop.
+		 */
+		if (errno != EEXIST)
+			break;
+		/*
+		 * This is a random value.  It is only necessary that
+		 * the next TMP_MAX values generated by adding 7777 to
+		 * VALUE are different with (module 2^32).
+		 */
+		value += 7777;
+	}
+	/* We return the null string if we can't find a unique file name.  */
+	pattern[0] = '\0';
+	return -1;
+}
+
+int git_mkstemp_mode(char *pattern, int mode)
+{
+	/* mkstemp is just mkstemps with no suffix */
+	return git_mkstemps_mode(pattern, 0, mode);
+}
+
+int gitmkstemps(char *pattern, int suffix_len)
+{
+	return git_mkstemps_mode(pattern, suffix_len, 0600);
+}
+
 int xmkstemp_mode(char *template, int mode)
 {
 	int fd;