X-Git-Url: http://git.draconx.ca/gitweb/dxcommon.git/blobdiff_plain/9efff8c7a48509fabab57631f5c64c669183dee0..27f6a9c3d4663286f1bec753fbd035ab1a6eb5de:/src/getline.h?ds=sidebyside

diff --git a/src/getline.h b/src/getline.h
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+++ b/src/getline.h
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+/*
+ * Copyright © 2024 Nick Bowler
+ *
+ * getline-like function which removes trailing newline (if any).
+ *
+ * If HAVE_GETLINE is not defined (or defined to 0) then a standard C
+ * implementation is used.  Othewrise, the POSIX getline function
+ * is called.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+#ifndef DX_GETLINE_H_
+#define DX_GETLINE_H_
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <limits.h>
+
+/*
+ * Size of the initial buffer allocated internally by the fallback
+ * implementation when *linebuf is NULL.
+ */
+#ifndef DX_GETLINE_INITIAL_ALLOC
+#  define DX_GETLINE_INITIAL_ALLOC 75
+#endif
+
+enum {
+	DX_GETLINE_OK     =  1,
+	DX_GETLINE_EOF    =  0,
+	DX_GETLINE_ERROR  = -1,
+	DX_GETLINE_ENOMEM = -2
+};
+
+/*
+ * Wrapper around getline with standard C fallback.
+ *
+ * Note that for portability to some getline implementations (e.g., FreeBSD)
+ * both *linebuf and *n should be set to zero on the initial call.
+ *
+ * If pre-allocating a buffer, ensure that its size is more than 1 byte,
+ * otherwise AIX 7.2 getline fails to work correctly.
+ *
+ * Returns 1 (DX_GETLINE_OK) if a line was read or 0 (DX_GETLINE_EOF) if
+ * no line could be read because the end of file was reached.
+ *
+ * On failure, returns a negative value.  If the C library input call failed
+ * then the return value is DX_GETLINE_ERROR and the reason for the failure
+ * should be available in errno.
+ *
+ * For the standard C fallback only, a return value of DX_GETLINE_ENOMEM
+ * indicates that the buffer allocation could not be expanded to fit the
+ * input line.
+ */
+static inline int dx_getline(char **linebuf, size_t *n, FILE *f)
+{
+#if HAVE_GETLINE
+	ssize_t rc;
+
+	if ((rc = getline(linebuf, n, f)) < 0) {
+		if (ferror(f))
+			return DX_GETLINE_ERROR;
+		return DX_GETLINE_EOF;
+	}
+
+	if (rc-- && (*linebuf)[rc] == '\n')
+		(*linebuf)[rc] = '\0';
+
+	return DX_GETLINE_OK;
+#else
+	char *work = *linebuf;
+	size_t pos = 0;
+	size_t sz;
+
+	if (!work) {
+		sz = DX_GETLINE_INITIAL_ALLOC;
+		goto initial_alloc;
+	}
+
+	for (sz = *n;;) {
+		if (!fgets(&work[pos], sz - pos, f)) {
+			if (ferror(f))
+				return DX_GETLINE_ERROR;
+
+			return pos ? DX_GETLINE_OK : DX_GETLINE_ERROR;
+		}
+
+		pos += strlen(&work[pos]);
+		if (work[pos-1] == '\n') {
+			work[pos-1] = '\0';
+			return DX_GETLINE_OK;
+		}
+
+		if (sz > INT_MAX/2 || sz > ((size_t)-1)/4)
+			break;
+
+		sz = ((sz*4) + 2) / 3;
+initial_alloc:
+		work = realloc(work, sz);
+		if (!work)
+			break;
+		*linebuf = work;
+		*n = sz;
+	}
+
+	return DX_GETLINE_ENOMEM;
+#endif
+}
+
+#endif