From: git <redacted>
Date: Sun, 3 May 2026 15:09:56 +0000 (-0400)
Subject: add fgetln
X-Git-Url: https://git.datadissipation.net/?a=commitdiff_plain;h=429122ae78262efcb3da5b67d6d746ba93cb209a;p=single-header-libcext.git

add fgetln
---

diff --git a/README.md b/README.md
index a10245f..cea3998 100644
--- a/README.md
+++ b/README.md
@@ -39,6 +39,12 @@ includes `vasprintf()` and `asprintf()`
 
 ---
 
+### fgetln
+
+includes `fgetln()`
+
+---
+
 ### getopt\_long
 
 includes `getopt()`, `getsubopt()`, `getopt_long()` and `getopt_long_only()`
@@ -54,14 +60,15 @@ permuting, defining those enables it per function (GNU behaviour, can still be d
 
 ---
 
-### strlcat
-
-includes `strlcat()` and `strlcpy()`
-
----
-
 ### strdup
 
 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.
+
+---
+
+### strlcat
+
+includes `strlcat()` and `strlcpy()`
diff --git a/fgetln.h b/fgetln.h
new file mode 100644
index 0000000..92a0f95
--- /dev/null
+++ b/fgetln.h
@@ -0,0 +1,94 @@
+/*
+ * Copyright (c) 1998 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to The NetBSD Foundation
+ * by Christos Zoulas.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/* https://git.datadissipation.net */
+#ifndef FGETLN_H_
+ #define FGETLN_H_      1
+
+ #ifdef FGETLN_INCLUDE_LIBC
+  #include <errno.h>
+  #include <stdio.h>
+  #include <stdlib.h>
+  #include <string.h>
+  #include <unistd.h>
+ #endif /* FGETLN_INCLUDE_LIBC */
+
+ #ifndef HAVE_FGETLN
+  #define HAVE_FGETLN   1
+  #define fgetln        i_fgetln_
+char *i_fgetln_(FILE *, size_t *);
+ #endif /* !HAVE_FGETLN */
+
+ #ifdef FGETLN_IMPLEMENTATION
+char *
+i_fgetln_(FILE *fp, size_t *len)
+{
+	static char *buf = NULL;
+	static size_t bufsiz = 0;
+	char *ptr;
+
+	if (buf == NULL) {
+		bufsiz = BUFSIZ;
+		if ((buf = malloc(bufsiz)) == NULL)
+			return NULL;
+	}
+
+	if (fgets(buf, bufsiz, fp) == NULL)
+		return NULL;
+
+	*len = 0;
+	while ((ptr = strchr(&buf[*len], '\n')) == NULL) {
+		size_t nbufsiz = bufsiz + BUFSIZ;
+		char *nbuf = realloc(buf, nbufsiz);
+
+		if (nbuf == NULL) {
+			int oerrno = errno;
+			free(buf);
+			errno = oerrno;
+			buf = NULL;
+			return NULL;
+		} else {
+			buf = nbuf;
+		}
+
+		if (fgets(&buf[bufsiz], BUFSIZ, fp) == NULL) {
+			buf[bufsiz] = '\0';
+			*len = strlen(buf);
+			return buf;
+		}
+
+		*len = bufsiz;
+		bufsiz = nbufsiz;
+	}
+
+	*len = (ptr - buf) + 1;
+	return buf;
+}
+ #endif /* FGETLN_IMPLEMENTATION */
+#endif /* !FGETLN_H_ */