git_mkstemps_mode(): replace magic numbers with computed value
The magic number "6" appears several times in the function, and is related to the size of the "XXXXXX" string we expect to find in the template. Let's pull that "XXXXXX" into a constant array, whose size we can get at compile time with ARRAY_SIZE(). Note that we probably can't just change this value, since callers will be feeding us a certain number of X's, but it hopefully makes the function itself easier to follow. While we're here, let's do the same with the "letters" array (which we _could_ modify if we wanted to include more characters). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Jeff King committed
Oct 2, 2019 at 11:32 UTC
53d687bf5f8008abd52b92120c7e22d4d81bdc71
1 file changed
+7
-5
wrapper.c
+7
-5
@@ -478,7 +478,9 @@ int git_mkstemps_mode(char *pattern, int suffix_len, int mode)
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"abcdefghijklmnopqrstuvwxyz"
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"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
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"0123456789";
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- static const int num_letters = 62;
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+ static const int num_letters = ARRAY_SIZE(letters) - 1;
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+ static const char x_pattern[] = "XXXXXX";
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+ static const int num_x = ARRAY_SIZE(x_pattern) - 1;
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uint64_t value;
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struct timeval tv;
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char *filename_template;
@@ -487,12 +489,12 @@ int git_mkstemps_mode(char *pattern, int suffix_len, int mode)
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len = strlen(pattern);
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- if (len < 6 + suffix_len) {
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+ if (len < num_x + suffix_len) {
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errno = EINVAL;
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return -1;
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}
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- if (strncmp(&pattern[len - 6 - suffix_len], "XXXXXX", 6)) {
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+ if (strncmp(&pattern[len - num_x - suffix_len], x_pattern, num_x)) {
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errno = EINVAL;
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return -1;
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}
@@ -503,12 +505,12 @@ int git_mkstemps_mode(char *pattern, int suffix_len, int mode)
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*/
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gettimeofday(&tv, NULL);
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value = ((uint64_t)tv.tv_usec << 16) ^ tv.tv_sec ^ getpid();
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- filename_template = &pattern[len - 6 - suffix_len];
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+ filename_template = &pattern[len - num_x - suffix_len];
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for (count = 0; count < TMP_MAX; ++count) {
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uint64_t v = value;
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int i;
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/* Fill in the random bits. */
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- for (i = 0; i < 6; i++) {
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+ for (i = 0; i < num_x; i++) {
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filename_template[i] = letters[v % num_letters];
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v /= num_letters;
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}