contrib: add "lar" - initial work on lua archive format

1 files changed, 176 insertions, 0 deletions

diff --git a/contrib/lar/lar.c b/contrib/lar/lar.c
new file mode 100644
index 000000000..255bc0150
--- /dev/null
+++ b/contrib/lar/lar.c
@@ -0,0 +1,176 @@
+#include "lar.h"
+
+int lar_read32( int fd, uint32_t *val )
+{
+	uint8_t buffer[5];
+
+	if( read(fd, buffer, 4) < 4 )
+		LAR_DIE("Unexpected EOF while reading data");
+
+	buffer[4] = 0;
+	*val = ntohl(*((uint32_t *) buffer));
+
+	return 0;
+}
+
+int lar_read16( int fd, uint16_t *val )
+{
+	uint8_t buffer[3];
+
+	if( read(fd, buffer, 2) < 2 )
+		LAR_DIE("Unexpected EOF while reading data");
+
+	buffer[2] = 0;
+	*val = ntohs(*((uint16_t *) buffer));
+
+	return 0;
+}
+
+lar_index * lar_get_index( lar_archive *ar )
+{
+	uint32_t i;
+	uint32_t idx_offset;
+	uint32_t idx_length;
+	lar_index *idx_map, *idx_ptr;
+
+	if( lseek(ar->fd, -(sizeof(idx_offset)), SEEK_END) == -1 )
+		LAR_DIE("Unable to seek to end of archive");
+
+	lar_read32(ar->fd, &idx_offset);
+	idx_length = ( ar->length - idx_offset - sizeof(idx_offset) );
+
+	if( lseek(ar->fd, idx_offset, SEEK_SET) == -1 )
+		LAR_DIE("Unable to seek to archive index");
+
+
+	idx_map = NULL;
+
+	for( i = 0; i < idx_length; \
+		i += (sizeof(lar_index) - sizeof(char)) 
+	) {
+		idx_ptr = (lar_index *)malloc(sizeof(lar_index));
+
+		lar_read32(ar->fd, &idx_ptr->noffset);
+		lar_read32(ar->fd, &idx_ptr->nlength);
+		lar_read32(ar->fd, &idx_ptr->foffset);
+		lar_read32(ar->fd, &idx_ptr->flength);
+		lar_read16(ar->fd, &idx_ptr->type);
+		lar_read16(ar->fd, &idx_ptr->flags);
+
+		idx_ptr->next = idx_map;
+		idx_map = idx_ptr;
+	}
+
+	return idx_map;
+}
+
+uint32_t lar_get_filename( lar_archive *ar,
+	lar_index *idx_ptr, char *filename 
+) {
+	if( idx_ptr->nlength >= LAR_FNAME_BUFFER )
+		LAR_DIE("Filename exceeds maximum allowed length");
+
+	if( lseek(ar->fd, idx_ptr->noffset, SEEK_SET) == -1 )
+		LAR_DIE("Unexpected EOF while seeking filename");
+
+	if( read(ar->fd, filename, idx_ptr->nlength) < idx_ptr->nlength )
+		LAR_DIE("Unexpected EOF while reading filename");
+
+	filename[idx_ptr->nlength] = 0;
+
+	return idx_ptr->nlength;
+}
+
+lar_member * lar_open_member( lar_archive *ar, const char *name )
+{
+	lar_index *idx_ptr = ar->index;
+	lar_member *member;
+	char memberfile[LAR_FNAME_BUFFER];
+	char *memberdata;
+	size_t pgsz  = getpagesize();
+
+	while(idx_ptr)
+	{
+		lar_get_filename(ar, idx_ptr, memberfile);
+
+		if( !strncmp(memberfile, name, idx_ptr->nlength) )
+		{
+			memberdata = mmap(
+				0, idx_ptr->flength + ( idx_ptr->foffset % pgsz ),
+				PROT_READ, MAP_PRIVATE,	ar->fd,
+				idx_ptr->foffset - ( idx_ptr->foffset % pgsz )
+			);
+
+			if( memberdata == MAP_FAILED )
+				LAR_DIE("Failed to mmap() member data");
+
+			member = (lar_member *)malloc(sizeof(lar_member));
+			member->type   = idx_ptr->type;
+			member->flags  = idx_ptr->flags;
+			member->length = idx_ptr->flength;
+			member->data   = &memberdata[idx_ptr->foffset % pgsz];
+
+			member->mmap   = memberdata;
+			member->mlen   = idx_ptr->flength + ( idx_ptr->foffset % pgsz );			
+
+			return member;
+		}
+
+		idx_ptr = idx_ptr->next;
+	}
+
+	return NULL;
+}
+
+int lar_close_member( lar_member *member )
+{
+	int stat = munmap(member->mmap, member->mlen);
+	free(member);
+
+	return stat;
+}
+
+lar_archive * lar_open( const char *filename )
+{
+	int fd;
+	struct stat as;
+	lar_archive *ar;
+	
+	if( stat(filename, &as) == -1 )
+		return NULL;
+
+	if( !(as.st_mode & S_IFREG) )
+		return NULL;
+
+	if( (fd = open(filename, O_RDONLY)) != -1 )
+	{
+		ar = (lar_archive *)malloc(sizeof(lar_archive));
+		ar->fd       = fd;
+		ar->length   = as.st_size;
+		ar->index    = lar_get_index(ar);
+		strncpy(ar->filename, filename, sizeof(ar->filename));
+
+		return ar;
+	}
+
+	return NULL;
+}
+
+int lar_close( lar_archive *ar )
+{
+	lar_index *idx_head;
+	lar_index *idx_next;
+
+	close(ar->fd);
+
+	idx_head = ar->index;
+	do {
+		idx_next = idx_head->next;
+		free(idx_head);
+	} while( (idx_head = idx_next) != NULL );
+
+	free(ar);
+
+	return 0;
+}
+