Initial commit

diff --git a/LICENSE b/LICENSE
new file mode 100644 (file)
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--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2023 Mattia Cabrini
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

diff --git a/Makefile b/Makefile
new file mode 100644 (file)
index 0000000..3529b6a
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,16 @@
+build: clear 
+       gcc -lc main.c -o main
+
+debug: clear
+       gcc -lc main.c -g -o main
+
+clear:
+       rm -f main
+
+all: build
+
+run: build
+       ./main main.c "cat main.c"
+
+run-debug: debug
+       gdb ./main main.c "cat main.c"

diff --git a/README.md b/README.md
new file mode 100644 (file)
index 0000000..b6e3ff7
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+++ b/README.md
@@ -0,0 +1,3 @@
+# Run @ Change
+
+Runs a command when a file changes.

diff --git a/main.c b/main.c
new file mode 100644 (file)
index 0000000..624b5ad
--- /dev/null
+++ b/main.c
@@ -0,0 +1,181 @@
+/*
+MIT License
+
+Copyright (c) 2023 Mattia Cabrini
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <limits.h>
+
+#include <sys/stat.h>
+#include <sys/inotify.h>
+
+typedef int bool;
+
+const int true = 1;
+const int false = 0;
+
+const char* init_watch(int *fd, int *wd, char *path) {
+       *fd = inotify_init();
+       
+       if (*fd == -1) {
+               return "could not init inotify watch";
+       }
+       
+       *wd = inotify_add_watch(*fd, path, IN_MODIFY | IN_IGNORED);
+
+       if (*wd == -1) {
+               close(*fd);
+               return "could not add a watch";
+       }
+
+       return NULL;
+}
+
+void close_watch(int *fd, int *wd) {
+       if (*wd >= 0) {
+               inotify_rm_watch(*fd, *wd);
+               *wd = -1;
+       }
+
+       if(*fd >= 0) {
+               close(*fd);
+               *fd = -1;
+       }
+}
+
+bool reg_file_exists(char *path, ino_t *st_ino) {
+       struct stat s;
+
+       int sres = stat(path, &s);
+
+       if (sres == -1) {
+               return false;
+       }
+
+       bool isreg = S_ISREG(s.st_mode);
+
+       if (st_ino != NULL) {
+               *st_ino = s.st_ino;
+       }
+
+       return isreg;
+}
+
+bool read_inotify_e(int fd, struct inotify_event *e) {
+       size_t sz_base_ev_struct = sizeof(struct inotify_event);
+       size_t sz_buf = sizeof(struct inotify_event) + NAME_MAX + 1;
+    
+       size_t bytes_read = read(fd, e, sz_base_ev_struct);
+
+       if (bytes_read != sz_base_ev_struct) {
+               return false;
+       }
+
+       if (e->len > 0) {
+               bytes_read = read(fd, e->name, e->len);
+
+               if (bytes_read != e->len) {
+                       return false;
+               }
+       }
+
+       return true;
+}
+
+// argv[1]: file path
+// argv[2]: command
+int main(int argc, char **argv) {
+       const char *err;
+       char *file_path;
+       
+       int fd;
+       int wd;
+       ino_t st_ino;
+
+       if (argc < 3) {
+               printf("Usage: run_at_change file_path comm...\n");
+               exit(1);
+       }
+       
+       file_path = argv[1];
+
+       printf("monitoring %s\n", file_path);
+
+       err = init_watch(&fd, &wd, file_path);
+
+       if (err != NULL) {
+               fprintf(stderr, "%s\n", err);
+               exit(1);
+       }
+
+       if (!reg_file_exists(file_path, &st_ino)) {
+               fprintf(stderr, "the file %s does not exist\n", file_path);
+               exit(1);
+       }
+       
+       size_t sz_buf = sizeof(struct inotify_event) + NAME_MAX + 1;
+       struct inotify_event *e = (struct inotify_event *) malloc(sz_buf);
+
+       while(read_inotify_e(fd, e)) {
+               if (e->wd != wd) {
+                       fprintf(stderr, "weird... e->wd != wd\n");
+                       continue;
+               }
+
+               if (e->mask & IN_MODIFY == 0) {
+                       fprintf(stderr, "weird... e->mask & IN_MODIFY == 0\n");
+                       continue;
+               } 
+       
+               if(e->mask & IN_MODIFY) {
+                       printf("changed\n");
+                       system(argv[2]);
+               } 
+
+               if(e->mask & IN_IGNORED) {
+                       printf("~~~ deleted\n");
+                       ino_t old_ino = st_ino;
+                       
+                       if (reg_file_exists(file_path, &st_ino)) {
+                               printf("~~~ file still exists\n");
+                               printf("~~~ ino %d :---> %d\n", old_ino, st_ino);
+                               
+                               close_watch(&fd, &wd);
+               
+                               err = init_watch(&fd, &wd, file_path);
+                               
+                               if (err != NULL) {
+                                       fprintf(stderr, "%s\n", err);
+                                       exit(1);
+                               }
+                       }
+                       
+                       system(argv[2]);
+               }
+       }
+       
+       close_watch(&fd, &wd);
+
+       return fd == 0 ? 1 : 0;
+}