Refactor project: build/install libspm[_static.a].so to make unit testing possible

1 files changed, 116 insertions, 0 deletions

diff --git a/lib/shell.c b/lib/shell.c
new file mode 100644
index 0000000..6b28e64
--- /dev/null
+++ b/lib/shell.c
@@ -0,0 +1,116 @@
+/**
+ * @file shell.c
+ */
+#include "spm.h"
+
+/**
+ * A wrapper for `popen()` that executes non-interactive programs and reports their exit value.
+ * To redirect stdout and stderr you must do so from within the `fmt` string
+ *
+ * ~~~{.c}
+ * int fd = 1;  // stdout
+ * const char *log_file = "log.txt";
+ * Process *proc_info;
+ * int status;
+ *
+ * // Send stderr to stdout
+ * shell(&proc_info, SHELL_OUTPUT, "foo 2>&1");
+ * // Send stdout and stderr to /dev/null
+ * shell(&proc_info, SHELL_OUTPUT,"bar &>/dev/null");
+ * // Send stdout from baz to log.txt
+ * shell(&proc_info, SHELL_OUTPUT, "baz %d>%s", fd, log_file);
+ * // Do not record or redirect output from any streams
+ * shell(&proc_info, SHELL_DEFAULT, "biff");
+ * ~~~
+ *
+ * @param Process uninitialized `Process` struct will be populated with process data
+ * @param options change behavior of the function
+ * @param fmt shell command to execute (accepts `printf` style formatters)
+ * @param ... variadic arguments (used by `fmt`)
+ */
+void shell(Process **proc_info, u_int64_t option, const char *fmt, ...) {
+    va_list args;
+    va_start(args, fmt);
+
+    clockid_t clkid = CLOCK_REALTIME;
+    FILE *proc = NULL;
+
+    (*proc_info) = (Process *)calloc(1, sizeof(Process));
+    if (!(*proc_info)) {
+        fprintf(SYSERROR);
+        exit(errno);
+    }
+    (*proc_info)->returncode = -1;
+
+    // outbuf needs to be an integer type because fgetc returns EOF (> char)
+    int *outbuf = (int *)calloc(1, sizeof(int));
+    if (!outbuf) {
+        fprintf(SYSERROR);
+        exit(errno);
+    }
+    char *cmd = (char *)calloc(PATH_MAX, sizeof(char));
+    if (!cmd) {
+        fprintf(SYSERROR);
+        exit(errno);
+    }
+
+    vsnprintf(cmd, PATH_MAX, fmt, args);
+
+    if (option & SHELL_BENCHMARK) {
+        if (clock_gettime(clkid, &(*proc_info)->start_time) == -1) {
+            perror("clock_gettime");
+            exit(errno);
+        }
+    }
+
+    proc = popen(cmd, "r");
+    if (!proc) {
+        free(outbuf);
+        va_end(args);
+        return;
+    }
+
+    if (option & SHELL_BENCHMARK) {
+        if (clock_gettime(clkid, &(*proc_info)->stop_time) == -1) {
+            perror("clock_gettime");
+            exit(errno);
+        }
+        (*proc_info)->time_elapsed = ((*proc_info)->stop_time.tv_sec - (*proc_info)->start_time.tv_sec)
+                                     + ((*proc_info)->stop_time.tv_nsec - (*proc_info)->start_time.tv_nsec) / 1E9;
+    }
+
+    if (option & SHELL_OUTPUT) {
+        size_t bytes_read = 0;
+        size_t i = 0;
+        size_t new_buf_size;
+        (*proc_info)->output = (char *)calloc(BUFSIZ, sizeof(char));
+
+        while ((*outbuf = fgetc(proc)) != EOF) {
+            if (i >= BUFSIZ) {
+                new_buf_size = BUFSIZ + (i + bytes_read);
+                (*proc_info)->output = (char *)realloc((*proc_info)->output, new_buf_size);
+                i = 0;
+            }
+            if (*outbuf) {
+                (*proc_info)->output[bytes_read] = (char)*outbuf;
+            }
+            bytes_read++;
+            i++;
+        }
+    }
+    (*proc_info)->returncode = pclose(proc);
+    va_end(args);
+    free(outbuf);
+    free(cmd);
+}
+
+/**
+ * Free process resources allocated by `shell()`
+ * @param proc_info `Process` struct
+ */
+void shell_free(Process *proc_info) {
+    if (proc_info->output) {
+        free(proc_info->output);
+    }
+    free(proc_info);
+}