can I pass argv from main to execv?
argv, c, exec, program-entry-point, setuid
Solution
Yes. The `argv` vector is always `NULL` terminated.
The draft C99 standard states:
If they are declared, the parameters to the `main` function shall obey the following constraints:
- The value of `argc` shall be nonnegative.
- `argv[argc]` shall be a null pointer.
Problem
The `execv()` function expects an array of `NULL` terminated strings but doesn't take the number of arguments. It uses a sentinel value (`NULL` pointer) to determine when the array ends. The man page for `execv()` states... The first argument, by convention, should point to the filename associated with the file being executed. The array of pointers must be terminated by a NULL pointer. ... so my question is.... I want to pass the `argv` from `main()` to `execv()`. Can I be assured that argv that comes into main is terminated by a NULL pointer? That is, can I be assured that `argv[argc] == NULL` or do I have to allocate my own `char*` array of size `argc` + 1 and put `NULL` in the `argc` index? If I can be assured, is it documented somewhere? Thanks, ~Eric