Implement decoding for lbximg.

[liblbx.git] / src / lbx.c

diff --git a/src/lbx.c b/src/lbx.c
index 20c32e75ae7deb69b8389a7a041f924840585414..3f947c1be269169970866b5a6be4e515a954f5c1 100644 (file)
--- a/src/lbx.c
+++ b/src/lbx.c
@@ -1,3 +1,7 @@
+#ifdef HAVE_CONFIG_H
+#      include "config.h"
+#endif
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -5,11 +9,14 @@
 #include <errno.h>
 #include <assert.h>
 
+#include <sys/stat.h>
+#include <sys/mman.h>
+
 #include "byteorder.h"
+#include "misc.h"
 #include "lbx.h"
 
 #define LBX_MAGIC 0x0000fead
-#define MIN(a,b) (((a)<(b))?(a):(b))
 
 int lbx_errno = 0;
 
@@ -162,43 +169,6 @@ int lbx_stat(struct lbx_state *lbx, size_t index, struct lbx_statbuf *buf)
        return 0;
 }
 
-/* Advance to the beginning of the index'th file by either fseek or reading. */
-static int _lbx_fseek(struct lbx_state *lbx, size_t base)
-{
-       static unsigned char oblivion[1024];
-       long dist;
-
-       if (lbx->foff < base) {
-               dist = base - lbx->foff;
-       } else if (lbx->foff > base) {
-               dist = -(long)(lbx->foff - base);
-       } else {
-               return 0;
-       }
-
-       if (fseek(lbx->f, dist, SEEK_CUR) == 0) {
-               lbx->foff += dist;
-       } else if (lbx->foff < base) {
-               while (dist) {
-                       size_t rc, amt = MIN(sizeof oblivion, dist);
-                       rc = fread(oblivion, 1, amt, lbx->f);
-                       lbx->foff += rc;
-                       dist -= rc;
-                       if (rc < amt) {
-                               if (feof(lbx->f))
-                                       lbx_errno = LBX_EEOF;
-                               else
-                                       lbx_errno = -errno;
-                               return -1;
-                       }
-               }
-       } else {
-               lbx_errno = -errno;
-               return -1;
-       }
-       return 0;
-}
-
 static size_t
 _lbx_mextract(struct lbx_state *lbx, size_t base, size_t len, FILE *of)
 {
@@ -222,7 +192,7 @@ _lbx_fextract(struct lbx_state *lbx, size_t base, size_t len, FILE *of)
 
        assert(lbx->f);
 
-       if (_lbx_fseek(lbx, base) == -1)
+       if (_lbx_fseek(lbx->f, &lbx->foff, base) == -1)
                return 0;
        
        while (len) {
@@ -265,12 +235,50 @@ size_t lbx_extract(struct lbx_state *lbx, size_t index, FILE *of)
        return _lbx_fextract(lbx, base, len, of);
 }
 
+void *lbx_mmap(struct lbx_state *lbx, size_t index, size_t *len)
+{
+       unsigned char *mapping;
+       struct stat statbuf;
+       size_t base;
+
+       if (index >= lbx->nfiles) {
+               lbx_errno = LBX_ERANGE;
+               return NULL;
+       }
+       
+       base = lbx->offsets[index];
+       *len = lbx->offsets[index+1] - lbx->offsets[index];
+
+       if (lbx->mem)
+               return lbx->mem + base;
+       
+       if (fstat(fileno(lbx->f), &statbuf) == -1) {
+               lbx_errno = -errno;
+               return NULL;
+       }
+
+       mapping = mmap(NULL, statbuf.st_size, PROT_READ, 0, fileno(lbx->f), 0);
+       if (mapping == MAP_FAILED) {
+               lbx_errno = -errno;
+               return NULL;
+       }
+
+       lbx->mem     = mapping;
+       lbx->memsize = statbuf.st_size;
+       return mapping + base;
+}
+
 void lbx_close(struct lbx_state *lbx)
 {
        if (!lbx) return;
 
-       if (lbx->f)
+       if (lbx->f) {
                fclose(lbx->f);
+               if (lbx->mem) {
+                       munmap(lbx->mem, lbx->memsize);
+               }
+       }
+
        free(lbx);
 }
 
@@ -284,6 +292,7 @@ const char *lbx_strerror(void)
        case LBX_EMAGIC:   return "Bad magic number";
        case LBX_EEOF:     return "Unexpected end-of-file";
        case LBX_ERANGE:   return "Index out of range";
+       case LBX_EFORMAT:  return "Invalid file format";
        }
 
        return "Unknown error";