Change read_package_field interface, and rewrite using low level functions

Fixes for a few bugs that have crept into dpkg in the last few days

2 files changed, 78 insertions, 14 deletions

diff --git a/libbb/libbb.h b/libbb/libbb.h
index a9c1a870f..bf5f0c1c5 100644
--- a/libbb/libbb.h
+++ b/libbb/libbb.h
@@ -245,7 +245,7 @@ char *unarchive(FILE *src_stream, FILE *out_stream, file_header_t *(*get_header)
 	const int extract_function, const char *prefix, char **extract_names);
 char *deb_extract(const char *package_filename, FILE *out_stream, const int extract_function,
 	const char *prefix, const char *filename);
-char *read_package_field(const char *package_buffer);
+int read_package_field(const char *package_buffer, char **field_name, char **field_value);
 char *fgets_str(FILE *file, const char *terminating_string);
 
 extern int unzip(FILE *l_in_file, FILE *l_out_file);
diff --git a/libbb/read_package_field.c b/libbb/read_package_field.c
index 3715230fe..f561df831 100644
--- a/libbb/read_package_field.c
+++ b/libbb/read_package_field.c
@@ -3,25 +3,89 @@
 #include "libbb.h"
 
 /*
- * Returns a [multi-line] package field
+ * Gets the next package field from package_buffer, seperated into the field name
+ * and field value, it returns the int offset to the first character of the next field
  */
-extern char *read_package_field(const char *package_buffer)
+int read_package_field(const char *package_buffer, char **field_name, char **field_value)
 {
-	int field_length = 0;	
-	int buffer_length = 0;
+	int offset_name_start = 0;
+	int offset_name_end = 0;
+	int offset_value_start = 0;
+	int offset_value_end = 0;
+	int offset = 0;
+	int next_offset;
+	int name_length;
+	int value_length;
+	int exit_flag = FALSE;
 
 	if (package_buffer == NULL) {
-		return(NULL);
+		*field_name = NULL;
+		*field_value = NULL;
+		return(-1);
 	}
-	buffer_length = strlen(package_buffer);
-	field_length = strcspn(package_buffer, "\n");
-	while (field_length < buffer_length) {
-		if (package_buffer[field_length + 1] != ' ') {
-			return(xstrndup(package_buffer, field_length));
+	while (1) {
+		next_offset = offset + 1;
+		switch (package_buffer[offset]) {
+			case('\0'):
+				exit_flag = TRUE;
+				break;
+			case(':'):
+				if (offset_name_end == 0) {
+					offset_name_end = offset;
+					offset_value_start = next_offset;
+				}
+				/* TODO: Name might still have trailing spaces if ':' isnt
+				 * immediately after name */
+				break;
+			case('\n'):
+				/* TODO: The char next_offset may be out of bounds */
+				if (package_buffer[next_offset] != ' ') {
+					exit_flag = TRUE;
+					break;
+				}
+			case('\t'):
+			case(' '):
+				/* increment the value start point if its a just filler */
+				if (offset_name_start == offset) {
+					offset_name_start++;
+				}
+				if (offset_value_start == offset) {
+					offset_value_start++;
+				}
+				break;
 		}
-		field_length++;
-		field_length += strcspn(&package_buffer[field_length], "\n");
+		if (exit_flag == TRUE) {
+			/* Check that the names are valid */
+			offset_value_end = offset;
+			name_length = offset_name_end - offset_name_start;
+			value_length = offset_value_end - offset_value_start;
+			if (name_length == 0) {
+				break;
+			}
+			if ((name_length > 0) && (value_length > 0)) {
+				break;
+			}
+
+			/* If not valid, start fresh with next field */
+			exit_flag = FALSE;
+			offset_name_start = offset + 1;
+			offset_name_end = 0;
+			offset_value_start = offset + 1;
+			offset_value_end = offset + 1;
+			offset++;
+		}
+		offset++;
+	}
+	if (name_length == 0) {
+		*field_name = NULL;
+	} else {
+		*field_name = xstrndup(&package_buffer[offset_name_start], name_length);
+	}
+	if (value_length > 0) {
+		*field_value = xstrndup(&package_buffer[offset_value_start], value_length);
+	} else {
+		*field_value = NULL;
 	}
-	return(xstrdup(package_buffer));
+	return(next_offset);
 }