X-Git-Url: https://git.draconx.ca/gitweb/liblbx.git/blobdiff_plain/c907294abea66bfa9739fcd6a08415f4ea1142f8..d89603e3f32d1ca27bcf684cad75ef5149de8a94:/src/lbx.c

diff --git a/src/lbx.c b/src/lbx.c
index 6e7b9ee..8ddcf18 100644
--- a/src/lbx.c
+++ b/src/lbx.c
@@ -3,17 +3,24 @@
 #include <string.h>
 #include <stdint.h>
 #include <errno.h>
+#include <assert.h>
+
+#include <sys/stat.h>
+#include <sys/mman.h>
 
 #include "byteorder.h"
 #include "lbx.h"
 
 #define LBX_MAGIC 0x0000fead
+#define MIN(a,b) (((a)<(b))?(a):(b))
 
 int lbx_errno = 0;
 
 struct lbx_state {
 	const char *name;
 
+	unsigned char *mem;
+	size_t memsize;
 	FILE *f;
 	long foff;
 
@@ -69,6 +76,59 @@ readerr:
 	return NULL;
 }
 
+static int _lbx_memcpy(void *dest, struct lbx_state *src, size_t size)
+{
+	if (src->foff + size > src->memsize)
+		return -1;
+	memcpy(dest, src->mem + src->foff, size);
+	src->foff += size;
+	return 0;
+}
+
+struct lbx_state *lbx_mopen(void *_mem, size_t size, const char *name)
+{
+	struct lbx_state *new = NULL;
+	struct lbx_state tmp = { .mem = _mem, .memsize = size };
+	uint16_t nfiles, version;
+	uint32_t magic;
+
+	if (_lbx_memcpy(&nfiles,  &tmp, sizeof nfiles)  == -1) goto eof;
+	if (_lbx_memcpy(&magic,   &tmp, sizeof magic)   == -1) goto eof;
+	if (_lbx_memcpy(&version, &tmp, sizeof version) == -1) goto eof;
+
+	nfiles  = letohs(nfiles);
+	magic   = letohl(magic);
+	version = letohs(version);
+
+	if (magic != LBX_MAGIC) {
+		lbx_errno = LBX_EMAGIC;
+		return NULL;
+	}
+	
+	new = malloc(sizeof *new + (nfiles+1)*(sizeof *new->offsets));
+	if (!new) {
+		lbx_errno = -errno;
+		return NULL;
+	}
+	
+	*new = (struct lbx_state){
+		.name    = name,
+		.nfiles  = nfiles,
+		.mem     = _mem,
+		.memsize = size,
+		.foff    = tmp.foff,
+	};
+	
+	if (_lbx_memcpy(new->offsets, new, (nfiles+1)*(sizeof *new->offsets)))
+		goto eof;
+
+	return new;
+eof:
+	free(new);
+	lbx_errno = LBX_EEOF;
+	return NULL;
+}
+
 struct lbx_state *lbx_open(const char *path)
 {
 	struct lbx_state *new = NULL;
@@ -89,11 +149,169 @@ size_t lbx_numfiles(struct lbx_state *lbx)
 	return lbx->nfiles;
 }
 
+int lbx_stat(struct lbx_state *lbx, size_t index, struct lbx_statbuf *buf)
+{
+	static char str[256]; /* FIXME */
+
+	if (index >= lbx->nfiles) {
+		buf->name = NULL;
+		lbx_errno = LBX_ERANGE;
+		return -1;
+	}
+
+	snprintf(str, sizeof str, "%s.%03d", lbx->name, index);
+	buf->name = str;
+	buf->size = lbx->offsets[index+1] - lbx->offsets[index];
+	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)
+{
+	size_t rc;
+
+	assert(lbx->mem);
+	assert(base + len <= lbx->memsize);
+
+	rc = fwrite(lbx->mem + base, 1, len, of);
+	if (rc < len)
+		lbx_errno = -errno;
+
+	return rc;
+}
+
+static size_t
+_lbx_fextract(struct lbx_state *lbx, size_t base, size_t len, FILE *of)
+{
+	unsigned char buf[1024];
+	size_t rc, written = 0;
+
+	assert(lbx->f);
+
+	if (_lbx_fseek(lbx, base) == -1)
+		return 0;
+	
+	while (len) {
+		size_t amt = MIN(len, sizeof buf);
+
+		rc = fread(buf, 1, amt, lbx->f);
+		lbx->foff += rc;
+		len -= rc;
+		if (rc < amt) {
+			if (feof(lbx->f)) lbx_errno = LBX_EEOF;
+			else lbx_errno = -errno;
+			break;
+		}
+
+		rc = fwrite(buf, 1, amt, of);
+		written += rc;
+		if (rc < amt) {
+			lbx_errno = -errno;
+			break;
+		}
+	}
+
+	return written;
+}
+
+size_t lbx_extract(struct lbx_state *lbx, size_t index, FILE *of)
+{
+	size_t base, len;
+
+	if (index >= lbx->nfiles) {
+		lbx_errno = LBX_ERANGE;
+		return 0;
+	}
+	
+	base = lbx->offsets[index];
+	len  = lbx->offsets[index+1] - lbx->offsets[index];
+
+	if (lbx->mem)
+		return _lbx_mextract(lbx, base, len, 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;
 
-	fclose(lbx->f);
+	if (lbx->f) {
+		fclose(lbx->f);
+		if (lbx->mem) {
+			munmap(lbx->mem, lbx->memsize);
+		}
+	}
+
 	free(lbx);
 }
 
@@ -106,6 +324,7 @@ const char *lbx_strerror(void)
 	case LBX_ESUCCESS: return "Success";
 	case LBX_EMAGIC:   return "Bad magic number";
 	case LBX_EEOF:     return "Unexpected end-of-file";
+	case LBX_ERANGE:   return "Index out of range";
 	}
 
 	return "Unknown error";