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cefe087d23
The fixargs() function is invoked when ksh needs to run a script without a #!/hashbang/path. Instead of letting the kernel invoke a shell, ksh exfile()s the script itself from sh_main(). In the forked child, it calls fixargs() to set the argument list in the environment to the args of the new script, so that 'ps' and /proc/PID/cmdline show the expected output. But fixargs() is broken because, on systems other than HP-UX (on which ksh uses pstat(2)), ksh simply inserts a terminating zero. The arguments list is not a zero-terminated C string. Unix systems expect the entire arguments buffer to be zeroed out, otherwise 'ps' and /proc/*/cmdline will have fragments of previous command lines in the output. The Red Hat patch for this bug is: https://src.fedoraproject.org/rpms/ksh/blob/642af4d6/f/ksh-20120801-argvfix.patch However, that fix is incomplete because 'command_len' was also hardcoded to be limited to 64 characters (!), which still gave invalid 'ps' output if the erased command line was longer. src/cmd/ksh93/sh/main.c: fixargs(): - Remove CMD_LENGTH macro which was defined as 64. - Remove code that limited the erasure of the arguments buffer to CMD_LENGTH characters. That code also had quite a dodgy strdup() call -- it copies arguments to the heap, but they are never freed (or even used), so it's a memory leak. Also, none of this is ever done if the length is calculated using pstat(2) on HP-UX, which is a clear indication that it's unnecessary. (I think this code block must have been some experiment they forgot to remove. One reason why I think so is that a 64 byte arguments limit never made sense, even in the 1980s when they wrote ksh on 80-column CRT displays. Another indication of this is that fixing it didn't require adding anything; the code to do the right thing was already there, it was just being overridden.) - Zero out the full arguments length as in the Red Hat patch. src/cmd/ksh93/tests/basic.sh: - Add test. It's sort of involved because 'ps' is one of the least portable commands in practice, in spite of standardisation. |
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| .. | ||
| argnod.h | ||
| builtins.h | ||
| defs.h | ||
| edit.h | ||
| fault.h | ||
| fcin.h | ||
| history.h | ||
| io.h | ||
| jobs.h | ||
| lexstates.h | ||
| name.h | ||
| national.h | ||
| nval.h | ||
| path.h | ||
| regress.h | ||
| shell.h | ||
| shlex.h | ||
| shnodes.h | ||
| shtable.h | ||
| streval.h | ||
| terminal.h | ||
| test.h | ||
| timeout.h | ||
| ulimit.h | ||
| variables.h | ||
| version.h | ||