Description:
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When compiling PHP 5.4.25 two compilation warnings are displayed indicating an invalid printf() conversion code 'k' being used. On lines 408 and 619 inside a spprintf() calls, the following lines are found in source file 'json.c':

409: int l = spprintf(&tmp, 0, "%.*k", (int) EG(precision), d);
619: len = spprintf(&d, 0, "%.*k", (int) EG(precision), dbl);

My suspicion is that the conversion code should be 'e', 'f' or 'g' instead of 'k' since the value seems to be a double being processed in both cases with a fixed precision.

While only a warning, this can certainly cause invalid floating point values to be returned, possibly even causing segmentation faults in spprintf().



Test script:
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Not needed.

Expected result:
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Hopefully somebody will fix the source who knows which proper printf() conversion code to use.

Actual result:
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Here's the 'make' line and the compiler's output for the file 'json.c':

/bin/bash /usr/local/src/php-5.4.25/libtool --silent --preserve-dup-deps --mode=compile cc  -Iext/json/ -I/usr/local/src/php-5.4.25/ext/json/ -DPHP_ATOM_INC -I/usr/local/src/php-5.4.25/include -I/usr/local/src/php-5.4.25/main -I/usr/local/src/php-5.4.25 -I/usr/local/src/php-5.4.25/ext/date/lib -I/usr/local/src/php-5.4.25/ext/ereg/regex -I/usr/include/libxml2 -I/usr/include/freetype2 -I/usr/local/src/php-5.4.25/ext/mbstring/oniguruma -I/usr/local/src/php-5.4.25/ext/mbstring/libmbfl -I/usr/local/src/php-5.4.25/ext/mbstring/libmbfl/mbfl -I/usr/include/mysql -I/usr/local/src/php-5.4.25/ext/sqlite3/libsqlite -I/usr/local/src/php-5.4.25/TSRM -I/usr/local/src/php-5.4.25/Zend    -I/usr/include -g -O2 -fvisibility=hidden  -c /usr/local/src/php-5.4.25/ext/json/json.c -o ext/json/json.lo 
/usr/local/src/php-5.4.25/ext/json/json.c: In function 'json_escape_string':
/usr/local/src/php-5.4.25/ext/json/json.c:408:6: warning: unknown conversion type character 'k' in format
/usr/local/src/php-5.4.25/ext/json/json.c: In function 'php_json_encode':
/usr/local/src/php-5.4.25/ext/json/json.c:619:6: warning: unknown conversion type character 'k' in format