forked from enlightenment/efl
reduce syscalls on opening files - roll CLOEXEC into open
on linux open supports() O_CLOEXEC. add test case for this in meson build and ifdef. this rolls 3 syscalls into 1 as we were doing open, then fnctl to get and fcntl to set flags. less syscalls is a good thing as syscalls are not cheap on some architectures or systems. I've seen a syscall on 1 system take 2-3x as long as another and another syscall in the same 2 system comparison take 10x as long. depending on the syscall you may only have a budget of something like 5000 syscalls "per frame" (60fps) before you spend all of your frame time just in syscalls not doing any processing, so we should keep these down if possible and that is what this does.
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24a49c8938
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@ -123,6 +123,20 @@ function_checks = [
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['dladdr', ['dlfcn.h'], ['dl'], '-D_GNU_SOURCE=1']
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]
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open_cloexec = cc.run('''#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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int main(int argc, char **argv) {
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int res = open(argv[0], O_RDONLY | O_CLOEXEC);
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if (res < 0) return 1;
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return 0;
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}
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''',
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name : 'open works with O_CLOEXEC')
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if open_cloexec.compiled() and open_cloexec.returncode() == 0
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config_h.set10('HAVE_OPEN_CLOEXEC', true)
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endif
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strerror_r_char_p = cc.compiles('''#define _GNU_SOURCE
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#include <string.h>
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int func (void)
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@ -802,19 +802,28 @@ eina_file_open(const char *path, Eina_Bool shared)
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if (!filename) return NULL;
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if (shared)
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{
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#ifdef HAVE_SHM_OPEN
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fd = shm_open(filename, O_RDONLY, S_IRWXU | S_IRWXG | S_IRWXO);
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if ((fd != -1) && (!eina_file_close_on_exec(fd, EINA_TRUE)))
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goto on_error;
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#else
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goto on_error;
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#endif
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}
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else
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{
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#ifdef HAVE_OPEN_CLOEXEC
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fd = open(filename, O_RDONLY, S_IRWXU | S_IRWXG | S_IRWXO | O_CLOEXEC);
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#else
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fd = open(filename, O_RDONLY, S_IRWXU | S_IRWXG | S_IRWXO);
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if ((fd != -1) && (!eina_file_close_on_exec(fd, EINA_TRUE)))
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goto on_error;
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#endif
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}
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if (fd < 0) goto on_error;
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if (!eina_file_close_on_exec(fd, EINA_TRUE))
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goto on_error;
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if (fstat(fd, &file_stat))
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goto on_error;
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@ -198,10 +198,16 @@ eina_mmap_safety_enabled_set(Eina_Bool enabled)
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/* no zero page device - open it */
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if (_eina_mmap_zero_fd < 0)
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{
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#ifdef HAVE_OPEN_CLOEXEC
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_eina_mmap_zero_fd = open("/dev/zero", O_RDWR | O_CLOEXEC);
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/* if we don;'t have one - fail to set up mmap safety */
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if (_eina_mmap_zero_fd < 0) return EINA_FALSE;
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#else
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_eina_mmap_zero_fd = open("/dev/zero", O_RDWR);
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/* if we don;'t have one - fail to set up mmap safety */
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if (_eina_mmap_zero_fd < 0) return EINA_FALSE;
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eina_file_close_on_exec(_eina_mmap_zero_fd, EINA_TRUE);
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#endif
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}
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/* set up signal handler for SIGBUS */
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sa.sa_sigaction = _eina_mmap_safe_sigbus;
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