Fix compile warning. #2574
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Fix compile warning. #2574
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In my opinion, this part should go into another commit, since it makes it unclear on how the warning was fixed. |
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The warning was fixed by assigning the return of the call to fgets to a variable. |
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../../../../github/wayfire/wayfire.git/src/debug.cpp: In function ‘std::string read_output(std::string)’: ../../../../github/wayfire/wayfire.git/src/debug.cpp:95:10: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’ declared with attribute ‘warn_unused_result’ [-Wunused-result] 95 | fgets(buffer, MAX_FUNCTION_NAME, file); | ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In this case there is a potential problem: if gets returns NULL, then nothing was read and the buffer is uninitialized. Not only would this function be returning uninitialized data, an arbitrary amount of memory could be allocated into line (and be returned) when std::string line = buffer; is searching for a terminating zero in the uninitialized buffer.
It was just because of the compiler warning fix that I was like: lets beautify this code a bit. Now it turned into a PR "test", adding a second commit to the same PR (because otherwise this obviously won't apply).
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thanks :) |
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Fix fixes the compile warning,
../../../../github/wayfire/wayfire.git/src/debug.cpp: In function ‘std::string read_output(std::string)’: ../../../../github/wayfire/wayfire.git/src/debug.cpp:95:10: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
95 | fgets(buffer, MAX_FUNCTION_NAME, file);
| ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In this case there is a potential problem: if gets returns NULL, then nothing was read and the buffer is uninitialized. Not only would this function be returning uninitialized data, an arbitrary amount of memory could be allocated into
line(and be returned) whenstd::string line = buffer;is searching for a terminating zero in the uninitialized buffer.I kinda rewrote this function (while I was at it) to not write first to the stack and then copy that into
line. Instead thestd::stringis created with the same space as the buffer was, and then we write directly into the allocated memory. Afterwards aresize()setslineto the correct size - removing any trailing newline at the same time.In other words, this code is much faster too (as if that was needed, but alas)!