Add alias file parsing function

Signed-off-by: Mattias Andrée <maandree@kth.se>

3 files changed, 152 insertions, 0 deletions

diff --git a/Makefile b/Makefile
index a76310f..27be8f9 100644
--- a/Makefile
+++ b/Makefile
@@ -29,6 +29,7 @@ PUBLIC_OBJ =\
 	libfonts_get_output_dpi.o\
 	libfonts_get_output_rendering_settings.o\
 	libfonts_get_subpixel_order_class.o\
+	libfonts_parse_alias_line.o\
 	libfonts_unget_subpixel_order_class.o\
 	libfonts_used_environs.o
 
diff --git a/libfonts.h b/libfonts.h
index a02bc19..3656d22 100644
--- a/libfonts.h
+++ b/libfonts.h
@@ -12,6 +12,12 @@
  */
 #define LIBFONTS_CONTEXT_VERSION 0
 
+/**
+ * File name of file in font directories that is used
+ * to create font aliases
+ */
+#define LIBFONTS_ALIAS_FILE_NAME "fonts.alias"
+
 
 #if defined(__clang__)
 # pragma clang diagnostic push
@@ -1676,6 +1682,32 @@ extern const char *const libfonts_used_environs[];
  */
 int libfonts_get_font_root_dirs(char ***, size_t *, struct libfonts_context *);
 
+/**
+ * Parse line from a font alias file
+ * 
+ * Font alias files are named "fonts.alias" (`LIBFONTS_ALIAS_FILE_NAME`)
+ * and are located in any font directory, i.e. directories returned by
+ * `libfonts_get_font_root_dirs` subdirectors (and further decedents)
+ * 
+ * @param   aliasp  Output parameter for the new alias
+ * @param   namep   Output parameter for the alias target,
+ *                  which can be ether a proper font name or an alias
+ * @param   line    The line to parse; parsing stops at the first
+ *                  newline or NUL byte
+ * @param   endp    Output parameter for the parsing end, i.e. the
+ *                  first newline or NUL byte in `line`
+ * @return          1 if the line included a font alias,
+ *                  0 if the line was blank or a comment line,
+ *                  -1 on failure
+ * 
+ * @throws  ENOMEM   Failed to allocate memory for `*aliasp` or `*namep`
+ * @throws  EBADMSG  The line is malformatted
+ * 
+ * `*aliasp` and `*namep` are set to `NULL` unless the function
+ * returns 1; `*endp` is updated even on failure
+ */
+int libfonts_parse_alias_line(char **, char **, const char *, char **);
+
 /* TODO add font listing */
 
 
diff --git a/libfonts_parse_alias_line.c b/libfonts_parse_alias_line.c
new file mode 100644
index 0000000..844a400
--- /dev/null
+++ b/libfonts_parse_alias_line.c
@@ -0,0 +1,119 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+#ifndef TEST
+
+
+int
+libfonts_parse_alias_line(char **aliasp, char **namep, const char *line, char **endp)
+{
+	const char *alias_start;
+	const char *alias_end;
+	const char *name_start;
+	const char *name_end;
+	int ret = 0;
+	size_t len;
+
+	if (aliasp)
+		*aliasp = NULL;
+	if (namep)
+		*namep = NULL;
+
+	while (isblank(*line))
+		line++;
+
+	if (!*line || *line == '!')
+		goto out;
+
+	if (*line == '"') {
+		alias_start = ++line;
+		while (*line && *line != '\n' && *line != '"')
+			line++;
+		if (*line != '"')
+			goto ebadmsg;
+		alias_end = line++;
+	} else {
+		alias_start = line;
+		while (*line && *line != '\n' && isblank(*line))
+			line++;
+		alias_end = line;
+	}
+
+	if (!isblank(*line))
+		goto ebadmsg;
+	do {
+		line++;
+	} while (isblank(*line));
+
+	if (*line == '"') {
+		name_start = ++line;
+		while (*line && *line != '\n' && *line != '"')
+			line++;
+		if (*line != '"')
+			goto ebadmsg;
+		name_end = line++;
+	} else {
+		name_start = line;
+		while (*line && *line != '\n' && isblank(*line))
+			line++;
+		name_end = line;
+	}
+
+	while (isblank(*line))
+		line++;
+	if (*line && *line != '\n')
+		goto ebadmsg;
+
+	if (aliasp) {
+		len = (size_t)(alias_end - alias_start);
+		*aliasp = malloc(len + 1);
+		if (!*aliasp)
+			goto enomem;
+		memcpy(*aliasp, alias_start, len);
+		(*aliasp)[len] = '\0';
+	}
+
+	if (namep) {
+		len = (size_t)(name_end - name_start);
+		*namep = malloc(len + 1);
+		if (!*namep)
+			goto enomem;
+		memcpy(*namep, name_start, len);
+		(*namep)[len] = '\0';
+	}
+
+	*endp = *(char **)(void *)&line;
+	return 1;
+
+ebadmsg:
+	errno = EBADMSG;
+	ret = -1;
+out:
+	while (*line && *line != '\n')
+		line++;
+out_at_end:
+	if (endp)
+		*endp = *(char **)(void *)&line;
+	return ret;
+
+enomem:
+	if (aliasp) {
+		free(*aliasp);
+		*aliasp = NULL;
+	}
+	errno = ENOMEM;
+	ret = -1;
+	goto out_at_end;
+}
+
+
+#else
+
+
+int
+main(void)
+{
+	return 0; /* XXX add test */
+}
+
+
+#endif