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ef1cafa736
Commit 72d751cba9 "build: rework library bundling" introduced a new helper binary "runas" whose sole purpose was mangling the argv vector passed to the actual called ELF image so that the renamed executable could obtain the proper name from argv[0]. This approach, however totally defeated the purpose of calling bundled ELF executables through the shipped ld.so loader since the execv() invocation performed by "runas" would cause the kernel the interprete the final program image through the system ELF loader again. To solve the problem, use an alternative approach of shipping a shared object "runas.so" which uses an ELF ".init_array" function pointer to obtain the argv[] vector of the to-be-executed main() function and mangle it in-place. The actual argv[0] value to use is communicated out-of-band using an environment variable "RUNAS_ARG0" by the shell wrapper script. The wrapper script also takes care of setting LD_PRELOAD to instruct the shipped ELF loader to preload the actual ELF program image with the "runas.so" helper library. Fixes FS#909. Signed-off-by: Jo-Philipp Wich <jo@mein.io>