1 files changed, 46 insertions, 0 deletions
diff --git a/src/shared.c b/src/shared.c
new file mode 100644
index 0000000..ee3c2f1
--- /dev/null
+++ b/src/shared.c
@@ -0,0 +1,46 @@
+#include "shared.h"
+
+#include <errno.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <string.h>
+
+void error(const char* format, ...) {
+    va_list list;
+    va_start(list, format);
+
+    vfprintf(stderr, format, list);
+    fprintf(stderr, "\n");
+    exit(EXIT_FAILURE);
+}
+
+FILE* get_file(const char* path, const char* type) {
+    FILE* file = fopen(path, type);
+    if (file == NULL) {
+        error("error: failed to open file %s: %s", path, strerror(errno));
+    }
+    return file;
+}
+
+long int get_number(const char* text) {
+    char* end;
+    long int n = strtol(text, &end, 10);
+    if (text == end) {
+        error("error: %s is not a valid number", text);
+    }
+    return n;
+}
+
+bool streql(const char* a, const char* b) {
+    if (*a != *b) return false;
+    int n = 0;
+    while (true) {
+        if (*(a+n) != *(b+n)) return false;
+        if (*(a+n) == '\0') return true;
+        ++n;
+    }
+}
+
+bool prefix(const char* pre, const char* str) {
+    return strncmp(pre, str, strlen(pre)) == 0;
+}