From: git <redacted>
Date: Wed, 6 May 2026 16:23:50 +0000 (-0400)
Subject: add strtonum
X-Git-Url: https://git.datadissipation.net/?a=commitdiff_plain;h=28d64df3a32817d7b21f95d0231d255710bfe4c2;p=single-header-libcext.git

add strtonum
---

diff --git a/README.md b/README.md
index cea3998..8324035 100644
--- a/README.md
+++ b/README.md
@@ -65,10 +65,16 @@ permuting, defining those enables it per function (GNU behaviour, can still be d
 includes `strdup()` and `strndup()`
 
 `strndup()` follows the latest standard, meaning that it copies at most _n_ chars, not _n_ + 1.
-also, no standard specifies that `strndup()` should return less than _n_ if `strlen(s) + 1` < _n_, but this implementation does so.
+Also, no standard specifies that `strndup()` should return less than _n_ if `strlen(s) + 1` < _n_, but this implementation does so.
 
 ---
 
 ### strlcat
 
 includes `strlcat()` and `strlcpy()`
+
+---
+
+### strtonum
+
+includes `strtonum()`
diff --git a/strtonum.h b/strtonum.h
new file mode 100644
index 0000000..2cea7dc
--- /dev/null
+++ b/strtonum.h
@@ -0,0 +1,78 @@
+/*
+ * Copyright (c) 2004 Ted Unangst and Todd Miller
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/* https://git.datadissipation.net */
+#ifndef STRTONUM_H_
+ #define STRTONUM_H_            1
+
+ #ifdef STRTONUM_INCLUDE_LIBC
+  #include <errno.h>
+  #include <limits.h>
+  #include <stdlib.h>
+ #endif /* STRTONUM_INCLUDE_LIBC */
+
+ #ifndef HAVE_STRTONUM
+ #define strtonum               i_strtonum_
+long long i_strtonum_(const char *numstr, long long minval, long long maxval,
+		      const char **errstrp);
+ #endif /* !HAVE_STRTONUM */
+
+ #ifdef STRTONUM_IMPLEMENTATION
+  #define	I_INVALID_	1
+  #define	I_TOOSMALL_	2
+  #define	I_TOOLARGE	3
+
+long long
+i_strtonum_(const char *numstr, long long minval, long long maxval,
+	    const char **errstrp)
+{
+	long long ll = 0;
+	int error = 0;
+	char *ep;
+	struct errval {
+		const char *errstr;
+		int err;
+	} ev[4] = {
+		{ NULL,		0 },
+		{ "invalid",	EINVAL },
+		{ "too small",	ERANGE },
+		{ "too large",	ERANGE },
+	};
+
+	ev[0].err = errno;
+	errno = 0;
+	if (minval > maxval) {
+		error = I_INVALID_;
+	} else {
+		ll = strtoll(numstr, &ep, 10);
+		if (numstr == ep || *ep != '\0')
+			error = I_INVALID_;
+		else if ((ll == LLONG_MIN && errno == ERANGE) || ll < minval)
+			error = I_TOOSMALL_;
+		else if ((ll == LLONG_MAX && errno == ERANGE) || ll > maxval)
+			error = I_TOOLARGE;
+	}
+	if (errstrp != NULL)
+		*errstrp = ev[error].errstr;
+	errno = ev[error].err;
+	if (error)
+		ll = 0;
+
+	return (ll);
+}
+ #endif /* STRTONUM_IMPLEMENTATION */
+#endif /* !STRTONUM_H_ */