implement POSIX polling dirmonitor #1926
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,142 @@ | ||
| #include <stdlib.h> | ||
| #include <string.h> | ||
| #include <fcntl.h> | ||
| #include <unistd.h> | ||
| #include <sys/stat.h> | ||
| #include <time.h> | ||
| #include <SDL.h> | ||
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| #define EVENT_MODIFIED (1 << 0) | ||
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| #if _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE > 700 || _POSIX_C_SOURCE >= 200809L | ||
| #define STAT_HAS_TIM | ||
| #endif | ||
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| struct file_info { | ||
| int fd; | ||
| dev_t dev; | ||
| ino_t ino; | ||
| struct timespec mtim; | ||
| int events; | ||
| }; | ||
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| struct dirmonitor_internal { | ||
| struct file_info* fds; | ||
| size_t fd_count; | ||
| }; | ||
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| struct dirmonitor_internal* init_dirmonitor() { | ||
| struct dirmonitor_internal* monitor = calloc(1, sizeof(struct dirmonitor_internal)); | ||
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| monitor->fd_count = 0; | ||
| monitor->fds = NULL; | ||
| return monitor; | ||
| } | ||
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| void deinit_dirmonitor(struct dirmonitor_internal* monitor) { | ||
| for (size_t i = 0; i < monitor->fd_count; ++i) | ||
| close(monitor->fds[i].fd); | ||
| free(monitor->fds); | ||
| } | ||
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| int get_changes_dirmonitor(struct dirmonitor_internal* monitor, char* buffer, int len) | ||
| { | ||
| struct stat new_stat; | ||
| int c = 0; | ||
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| for (size_t i = 0; i < monitor->fd_count; ++i) { | ||
| if (monitor->fds[i].fd < 0) | ||
| continue; | ||
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| fstat(monitor->fds[i].fd, &new_stat); | ||
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| if ( | ||
| new_stat.st_mtime > monitor->fds[i].mtim.tv_sec || | ||
| #ifdef STAT_HAS_TIM | ||
| (new_stat.st_mtim.tv_sec == monitor->fds[i].mtim.tv_sec && new_stat.st_mtim.tv_nsec > monitor->fds[i].mtim.tv_nsec) || | ||
| #endif | ||
| new_stat.st_dev != monitor->fds[i].dev || // device changed | ||
| new_stat.st_ino != monitor->fds[i].ino || // inode changed | ||
| 0 | ||
| ) { | ||
| monitor->fds[i].mtim.tv_sec = new_stat.st_mtime; | ||
| #ifdef STAT_HAS_TIM | ||
| monitor->fds[i].mtim.tv_nsec = new_stat.st_mtim.tv_nsec; | ||
| #endif | ||
| monitor->fds[i].dev = new_stat.st_dev; | ||
| monitor->fds[i].ino = new_stat.st_ino; | ||
| monitor->fds[i].events |= EVENT_MODIFIED; | ||
| c += 1; | ||
| } | ||
| } | ||
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| if (!c) | ||
| SDL_Delay(100); | ||
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| return c; | ||
| } | ||
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| int translate_changes_dirmonitor(struct dirmonitor_internal* monitor, char* buffer, int count, int (*change_callback)(int, const char*, void*), void* data) { | ||
| for (size_t i = 0; i < monitor->fd_count; ++i) { | ||
| if (monitor->fds[i].events & EVENT_MODIFIED) { | ||
| --count; | ||
| monitor->fds[i].events = monitor->fds[i].events & ~ EVENT_MODIFIED; | ||
| change_callback(monitor->fds[i].fd, NULL, data); | ||
| } | ||
| } | ||
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| return 0; | ||
| } | ||
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| int add_dirmonitor(struct dirmonitor_internal* monitor, const char* path) | ||
| { | ||
| int fd = open(path, O_RDONLY | O_NOFOLLOW); | ||
| if (fd == -1) | ||
| return -1; | ||
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| // Check if there is any space we can reuse | ||
| for (size_t i = 0; i < monitor->fd_count; ++i) { | ||
| if (monitor->fds[i].fd == -1) { | ||
| monitor->fds[i].fd = fd; | ||
| monitor->fds[i].mtim.tv_sec = 0; | ||
| return fd; | ||
| } | ||
| } | ||
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| // There is no empty space, add a new entry; | ||
| // Prepare a new list before switching it to prevent race conditions | ||
| struct file_info* old_fds = monitor->fds; | ||
| struct file_info* new_fds; | ||
| new_fds = malloc(sizeof(*new_fds) * (monitor->fd_count + 1)); | ||
|
There was a problem hiding this comment. Still not too sure about just allocating one more space. |
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| if (old_fds) | ||
| memcpy(new_fds, old_fds, sizeof(*new_fds) * (monitor->fd_count)); | ||
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| new_fds[monitor->fd_count].fd = fd; | ||
| new_fds[monitor->fd_count].mtim.tv_sec = 0; | ||
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| monitor->fds = new_fds; | ||
| free(old_fds); | ||
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| monitor->fd_count++; | ||
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| return fd; | ||
| } | ||
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| void remove_dirmonitor(struct dirmonitor_internal* monitor, int fd) | ||
| { | ||
| for (size_t i = 0; i < monitor->fd_count; ++i) { | ||
| if (monitor->fds[i].fd == fd) { | ||
| int fd = monitor->fds[i].fd; | ||
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| monitor->fds[i].fd = -1; | ||
| monitor->fds[i].events = 0; | ||
| close(fd); | ||
| return; | ||
| } | ||
| } | ||
| } | ||
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| int get_mode_dirmonitor() { | ||
| return 2; | ||
| } | ||
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Could
fd_countbe raced over?Same with the
fdsstructs.For example:
get_changes_dirmonitoradd_dirmonitoradd_dirmonitorneeds to allocate new space, so it does, but still doesn't switch it outget_changes_dirmonitorsavesfdsin a registeradd_dirmonitorswitches out the spaces, frees the oldfdsget_changes_dirmonitoruses thefdsfrom the register, SIGSEGVs.