diff options
author | Tom Lane | 2005-12-05 21:57:00 +0000 |
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committer | Tom Lane | 2005-12-05 21:57:00 +0000 |
commit | 8c2d8dcfda2ca398a66bbb2600c2a6f4ac692c95 (patch) | |
tree | 168faf40651d2674976ba5f041cac77e12298175 | |
parent | 4ea49802eb25adbdd88928984eb57de26512c58c (diff) |
Document return-value conventions used by this implementation, per
suggestion from Bruce.
-rw-r--r-- | src/port/snprintf.c | 26 |
1 files changed, 23 insertions, 3 deletions
diff --git a/src/port/snprintf.c b/src/port/snprintf.c index 90d1cf5dbe..91adde197a 100644 --- a/src/port/snprintf.c +++ b/src/port/snprintf.c @@ -51,9 +51,8 @@ * SNPRINTF, VSNPRINTF and friends * * These versions have been grabbed off the net. They have been - * cleaned up to compile properly and support for most of the Single - * Unix Specification has been added. Remaining unimplemented features - * are: + * cleaned up to compile properly and support for most of the Single Unix + * Specification has been added. Remaining unimplemented features are: * * 1. No locale support: the radix character is always '.' and the ' * (single quote) format flag is ignored. @@ -65,6 +64,27 @@ * 4. No support for "long double" ("Lf" and related formats). * * 5. Space and '#' flags are not implemented. + * + * + * The result values of these functions are not the same across different + * platforms. This implementation is compatible with the Single Unix Spec: + * + * 1. -1 is returned only if processing is abandoned due to an invalid + * parameter, such as incorrect format string. (Although not required by + * the spec, this happens only when no characters have yet been transmitted + * to the destination.) + * + * 2. For snprintf and sprintf, 0 is returned if str == NULL or count == 0; + * no data has been stored. + * + * 3. Otherwise, the number of bytes actually transmitted to the destination + * is returned (excluding the trailing '\0' for snprintf and sprintf). + * + * For snprintf with nonzero count, the result cannot be more than count-1 + * (a trailing '\0' is always stored); it is not possible to distinguish + * buffer overrun from exact fit. This is unlike some implementations that + * return the number of bytes that would have been needed for the complete + * result string. */ /************************************************************** |