cmdline.c: add getdelim code for old macOS

lib/cmdline.c

@@ -50,6 +50,100 @@
 #include "treemerge.h"
 #include "utilities.h"
 
+#if defined(__APPLE__)
+#include <AvailabilityMacros.h>
+#if (MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_7)
+/* there is no getdelim */
+#if __STDC_VERSION__ >= 199901L
+/* restrict is a keyword */
+#else
+# define restrict
+#endif
+
+#ifndef _POSIX_SOURCE
+typedef long ssize_t;
+#define SSIZE_MAX LONG_MAX
+#endif
+
+ssize_t getdelim(char **restrict lineptr, size_t *restrict n, int delimiter,
+                 FILE *restrict stream);
+ssize_t getline(char **restrict lineptr, size_t *restrict n,
+                FILE *restrict stream);
+
+#define _GETDELIM_GROWBY 128    /* amount to grow line buffer by */
+#define _GETDELIM_MINLEN 4      /* minimum line buffer size */
+
+ssize_t getdelim(char **restrict lineptr, size_t *restrict n, int delimiter,
+                 FILE *restrict stream)
+{
+	char *buf, *pos;
+	int c;
+	ssize_t bytes;
+
+	if (lineptr == NULL || n == NULL) {
+		errno = EINVAL;
+		return -1;
+	}
+	if (stream == NULL) {
+		errno = EBADF;
+		return -1;
+	}
+
+	/* resize (or allocate) the line buffer if necessary */
+	buf = *lineptr;
+	if (buf == NULL || *n < _GETDELIM_MINLEN) {
+		buf = realloc(*lineptr, _GETDELIM_GROWBY);
+		if (buf == NULL) {
+			/* ENOMEM */
+			return -1;
+		}
+		*n = _GETDELIM_GROWBY;
+		*lineptr = buf;
+	}
+
+	/* read characters until delimiter is found, end of file is reached, or an error occurs. */
+	bytes = 0;
+	pos = buf;
+	while ((c = getc(stream)) != EOF) {
+		if (bytes + 1 >= SSIZE_MAX) {
+			errno = EOVERFLOW;
+			return -1;
+		}
+		bytes++;
+		if (bytes >= *n - 1) {
+			buf = realloc(*lineptr, *n + _GETDELIM_GROWBY);
+			if (buf == NULL) {
+				/* ENOMEM */
+				return -1;
+			}
+			*n += _GETDELIM_GROWBY;
+			pos = buf + bytes - 1;
+			*lineptr = buf;
+		}
+
+		*pos++ = (char) c;
+		if (c == delimiter) {
+			break;
+		}
+	}
+
+	if (ferror(stream) || (feof(stream) && (bytes == 0))) {
+		/* EOF, or an error from getc(). */
+		return -1;
+	}
+
+	*pos = '\0';
+	return bytes;
+}
+
+ssize_t getline(char **restrict lineptr, size_t *restrict n,
+                FILE *restrict stream)
+{
+	return getdelim(lineptr, n, '\n', stream);
+}
+#endif
+#endif
+
 /* define paranoia levels */
 static const RmDigestType RM_PARANOIA_LEVELS[] = {RM_DIGEST_METRO,
                                                   RM_DIGEST_METRO256,