Factorize integer argument parsing

Add util functions for integer parsing (with tests), and factorize
integer argument parsing to avoid code duplication.

app/src/util/str_util.c

@@ -1,5 +1,7 @@
 #include "str_util.h"
 
+#include <errno.h>
+#include <limits.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -60,6 +62,59 @@ strquote(const char *src) {
     return quoted;
 }
 
+bool
+parse_integer(const char *s, long *out) {
+    char *endptr;
+    if (*s == '\0') {
+        return false;
+    }
+    errno = 0;
+    long value = strtol(s, &endptr, 0);
+    if (errno == ERANGE) {
+        return false;
+    }
+    if (*endptr != '\0') {
+        return false;
+    }
+
+    *out = value;
+    return true;
+}
+
+bool
+parse_integer_with_suffix(const char *s, long *out) {
+    char *endptr;
+    if (*s == '\0') {
+        return false;
+    }
+    errno = 0;
+    long value = strtol(s, &endptr, 0);
+    if (errno == ERANGE) {
+        return false;
+    }
+    int mul = 1;
+    if (*endptr != '\0') {
+        if (s == endptr) {
+            return false;
+        }
+        if ((*endptr == 'M' || *endptr == 'm') && endptr[1] == '\0') {
+            mul = 1000000;
+        } else if ((*endptr == 'K' || *endptr == 'k') && endptr[1] == '\0') {
+            mul = 1000;
+        } else {
+            return false;
+        }
+    }
+
+    if ((value < 0 && LONG_MIN / mul > value) ||
+        (value > 0 && LONG_MAX / mul < value)) {
+        return false;
+    }
+
+    *out = value * mul;
+    return true;
+}
+
 size_t
 utf8_truncation_index(const char *utf8, size_t max_len) {
     size_t len = strlen(utf8);

app/src/util/str_util.h

@@ -1,6 +1,7 @@
 #ifndef STRUTIL_H
 #define STRUTIL_H
 
+#include <stdbool.h>
 #include <stddef.h>
 
 #include "config.h"
@@ -25,6 +26,18 @@ xstrjoin(char *dst, const char *const tokens[], char sep, size_t n);
 char *
 strquote(const char *src);
 
+// parse s as an integer into value
+// returns true if the conversion succeeded, false otherwise
+bool
+parse_integer(const char *s, long *out);
+
+// parse s as an integer into value
+// like parse_integer(), but accept 'k'/'K' (x1000) and 'm'/'M' (x1000000) as
+// suffix
+// returns true if the conversion succeeded, false otherwise
+bool
+parse_integer_with_suffix(const char *s, long *out);
+
 // return the index to truncate a UTF-8 string at a valid position
 size_t
 utf8_truncation_index(const char *utf8, size_t max_len);