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author | Harald van Dijk <harald@gigawatt.nl> | 2013-08-23 20:30:28 +1000 |
---|---|---|
committer | Ben Hutchings <ben@decadent.org.uk> | 2020-03-28 21:42:54 +0000 |
commit | a436ea0721c8d7ff6d0d9e4d46d8ae4655e8a73a (patch) | |
tree | b6077755fbfa4f68737e5a3d3ea4621a59fb4948 | |
parent | a4e6b2aab296a5adc38372b157a854eb82054020 (diff) | |
download | klibc-a436ea0721c8d7ff6d0d9e4d46d8ae4655e8a73a.tar.gz |
[klibc] dash: [BUILTIN] Use PRIdMAX instead of %j in printf
[ dash commit 5464ae7d9e226586b79527cb445d892177b70271 ]
On 12/03/2012 05:59 PM, Harald van Dijk wrote:
> On 12/03/2012 08:42 AM, Roy wrote:
>> MSYS libc does not support %j[dXx] format, only %ll[dXx] is supported.
>>
>> diff --git a/src/bltin/printf.c b/src/bltin/printf.c
>> index 893295c..12ce660 100644
>> --- a/src/bltin/printf.c
>> +++ b/src/bltin/printf.c
>> @@ -319,11 +319,12 @@ mklong(const char *str, const char *ch)
>> char *copy;
>> size_t len;
>>
>> - len = ch - str + 3;
>> + len = ch - str + 4;
>> STARTSTACKSTR(copy);
>> copy = makestrspace(len, copy);
>> - memcpy(copy, str, len - 3);
>> - copy[len - 3] = 'j';
>> + memcpy(copy, str, len - 4);
>> + copy[len - 4] = 'l';
>> + copy[len - 3] = 'l';
>> copy[len - 2] = *ch;
>> copy[len - 1] = '\0';
>> return (copy);
>
> The calling code uses the result to print intmax_t and uintmax_t values.
> Printing intmax_t values with %lld is wrong, this will only work if
> intmax_t is really a typedef for long long (which may be true on your
> system, but is not required by the standard).
>
> The other patch that Jonathan linked to should work just fine.
Here's a slightly tweaked version of that patch. Regardless of whether
PRIdMAX is defined as "jd" or as "lld", the use of memcpy here, first
copying "jd"/"lld" and the null byte, and only changing the 'd' after
that, surprisingly results in slightly shorter object code than the
original byte-by-byte approach, even though memcpy is fully inlined.
Perhaps that could be a reason for applying this, even if the original
reason for it, making the code work on not-quite-conforming systems,
isn't good enough to get it in dash.
Tested with normal glibc, and with glibc hacked to not provide PRIdMAX.
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
-rw-r--r-- | usr/dash/bltin/printf.c | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/usr/dash/bltin/printf.c b/usr/dash/bltin/printf.c index dcff099248c5c..add89095915db 100644 --- a/usr/dash/bltin/printf.c +++ b/usr/dash/bltin/printf.c @@ -320,16 +320,24 @@ out: static char * mklong(const char *str, const char *ch) { + /* + * Replace a string like "%92.3u" with "%92.3"PRIuMAX. + * + * Although C99 does not guarantee it, we assume PRIiMAX, + * PRIoMAX, PRIuMAX, PRIxMAX, and PRIXMAX are all the same + * as PRIdMAX with the final 'd' replaced by the corresponding + * character. + */ + char *copy; size_t len; - len = ch - str + 3; + len = ch - str + sizeof(PRIdMAX); STARTSTACKSTR(copy); copy = makestrspace(len, copy); - memcpy(copy, str, len - 3); - copy[len - 3] = 'j'; + memcpy(copy, str, len - sizeof(PRIdMAX)); + memcpy(copy + len - sizeof(PRIdMAX), PRIdMAX, sizeof(PRIdMAX)); copy[len - 2] = *ch; - copy[len - 1] = '\0'; return (copy); } |