minecraft-pi-reborn/libreborn/src/util/exec.c

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#include <libreborn/exec.h>
// Safe execvpe()
__attribute__((noreturn)) void safe_execvpe(const char *const argv[], const char *const envp[]) {
int ret = execvpe(argv[0], (char *const *) argv, (char *const *) envp);
if (ret == -1) {
ERR("Unable To Execute Program: %s: %s", argv[0], strerror(errno));
} else {
IMPOSSIBLE();
}
}
// Chop Off Last Component
void chop_last_component(char **str) {
size_t length = strlen(*str);
for (size_t i = 0; i < length; i++) {
size_t j = length - i - 1;
if ((*str)[j] == '/') {
(*str)[j] = '\0';
break;
}
}
}
// Get Binary Directory (Remember To Free)
char *get_binary_directory() {
// Get Path To Current Executable
char *exe = realpath("/proc/self/exe", NULL);
ALLOC_CHECK(exe);
// Chop Off Last Component
chop_last_component(&exe);
// Return
return exe;
}
// Safe execvpe() Relative To Binary
__attribute__((noreturn)) void safe_execvpe_relative_to_binary(const char *const argv[], const char *const envp[]) {
// Get Binary Directory
char *binary_directory = get_binary_directory();
// Create Full Path
char *full_path = NULL;
safe_asprintf(&full_path, "%s/%s", binary_directory, argv[0]);
// Free Binary Directory
free(binary_directory);
// Build New argv
int argc;
for (argc = 0; argv[argc] != NULL; argc++);
const char *new_argv[argc + 1];
for (int i = 1; i < argc; i++) {
new_argv[i] = argv[i];
}
new_argv[0] = full_path;
new_argv[argc] = NULL;
// Run
safe_execvpe(new_argv, envp);
}
// Get MCPI Directory
char *get_mcpi_directory() {
return getenv("MCPI_DIRECTORY");
}
// Run Command And Get Output
char *run_command(const char *const command[], int *return_code) {
// Store Output
int output_pipe[2];
safe_pipe2(output_pipe, 0);
// Run
pid_t ret = fork();
if (ret == -1) {
ERR("Unable To Run Command: %s", strerror(errno));
} else if (ret == 0) {
// Child Process
// Pipe stdout
dup2(output_pipe[1], STDOUT_FILENO);
close(output_pipe[0]);
close(output_pipe[1]);
// Close stderr (But Not In Debug Mode)
const char *is_debug = getenv("MCPI_DEBUG");
if (is_debug == NULL || strlen(is_debug) < 1) {
int null_fd = open("/dev/null", O_WRONLY);
dup2(null_fd, STDERR_FILENO);
close(null_fd);
}
// Run
safe_execvpe(command, (const char *const *) environ);
} else {
// Parent Process
// Read stdout
close(output_pipe[1]);
char *output = NULL;
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#define BUFFER_SIZE 1024
char buf[BUFFER_SIZE];
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int bytes_read = 0;
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while ((bytes_read = read(output_pipe[0], (void *) buf, BUFFER_SIZE - 1 /* Account For NULL-Terminator */)) > 0) {
buf[bytes_read] = '\0';
string_append(&output, "%s", buf);
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}
close(output_pipe[0]);
// Get Return Code
int status;
waitpid(ret, &status, 0);
*return_code = WIFEXITED(status) ? WEXITSTATUS(status) : -1;
// Return
return output;
}
}