replace strings in ELF .rodata sections #1344
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Have confirmed that
(There is a build error relating to the installation of |
replacement string needs one more byte also
ahgamut
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Jan 11, 2025
jart/cosmopolitan#1344 the renamestr program written in the above PR means the build process for binaries in superconfigure does not require the existence of /zip or equivalent folder as an absolute path to copy necessary assets. we build the binaries setting $COSMOS as the target folder for all files and then patch the .rodata section in the debug binaries right before running apelink (actually, we run apelink with copies of the binaries so that the originals can be used like regular ELF binaries installed on a traditional Linux system.) Now, assuming binfmt_misc details are satisfied, we should be able to build software without needing sudo. /zip was needed in the build configuration of packages because it was (at the time) the only way to ensure the final APE binary had correct locations for reading assets. But /zip had several side effects: need of sudo for creating the folder, COSMOPOLITAN_DISABLE_ZIPOS=1 for all steps of superconfigure, debug binaries were difficult to use in case we needed to fix a bug, some build flakes due to builds writing files to the same subfolder of /zip, et cetera. Now, the build procedure of superconfigure should (ideally) result in ELF binaries installed from using cosmocc, and the /zip features are activated right when the fat binary is created, which means finding errors is far more streamlined
jart
reviewed
Jan 12, 2025
also use a string struct
if the string to replace is at the absolute end of the .rodata section, it may not have a null terminating byte. In that case alone, we replace one less byte than earlier, so as to avoid overwriting some other data.
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With
tool/build/renamestr(or an equivalent feature), I hope to avoid the/zipfolder when building binaries with https://github.com/ahgamut/superconfigure. Most of the folder locations involving/zipare stored in the.rodatasection of the ELF binary, and/zipis more useful for the APE than the debug ELF binaries.The current build process on
superconfigureinvolves:/zipfolder using sudoterminfoentries, SSL certs) is copied to/zip/zipfolder (or crash)With this PR, the build process hopefully becomes:
/zipfolder with sudo$LOCATION/superconfigure/cosmos/$ARCH/$SUBFOLDER)renamestron the ELF binary to replace$LOCATION/superconfigure/cosmos/$ARCH/to/zip, before runningapelinkPerhaps this feature can be part of
apelinkitself (the structure and some code ofrenamestris copied fromapelink), but I wrote a separate tool in a draft PR, for an initial exploration.