execve.2: execve also returns E2BIG if a string is too long #37
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The execve syscall returns -E2BIG in 3 cases: - The total length of the command line arguments and environment is too large. - An argument or environment string (including the NUL byte) is longer than MAX_ARG_STRLEN. - The full path to the executable (including the NUL byte) exceeds MAX_ARG_STRLEN. Spell out all 3 cases in the -E2BIG section. Discovered by moving a too large commandline parameter to an environment variable, and finding that things still did not work. Examined the code in fs/exec.c to get the details. This simple shell script starts failing at 2^17 on a system with 4kB page size: ./exec2big.sh: line 10: /bin/true: Argument list too long fork failed at loop 17 STRING="a" for loop in `seq 20`; do STRING="$STRING$STRING" export STRING if /bin/true ; then : # still under the limit else echo "fork failed at loop $loop" fi done Signed-off-by: Rik van Riel <riel@surriel.com> Suggested-by: Matthew House <mattlloydhouse@gmail.com>
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Document that if a command line or environment string is too long (> MAX_ARG_STRLEN), execve will also return E2BIG.