From: Nick Bowler <draconx@gmail.com>
Date: Sat, 29 Dec 2007 23:08:48 +0000 (-0500)
Subject: Split off _lbx_fseek() into a shared component of the library.
X-Git-Url: https://git.draconx.ca/gitweb/liblbx.git/commitdiff_plain/8456fd3535202bc2b79df4ddb794cbfd075054fd

Split off _lbx_fseek() into a shared component of the library.
---

diff --git a/src/Makefile.am b/src/Makefile.am
index 6867d30..8bec700 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -2,7 +2,7 @@ lib_LTLIBRARIES   = liblbx.la
 bin_PROGRAMS      = lbxtool
 include_HEADERS   = lbx.h
 
-liblbx_la_SOURCES = byteorder.h lbx.c image.c
+liblbx_la_SOURCES = byteorder.h misc.h misc.c lbx.c image.c
 
 lbxtool_SOURCES   = lbxtool.c
 lbxtool_LDADD     = liblbx.la
diff --git a/src/lbx.c b/src/lbx.c
index 253da5e..d3815a9 100644
--- a/src/lbx.c
+++ b/src/lbx.c
@@ -13,10 +13,10 @@
 #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;
 
@@ -169,43 +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)
 {
@@ -229,7 +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) {
diff --git a/src/lbx.h b/src/lbx.h
index 78e4502..ec525d0 100644
--- a/src/lbx.h
+++ b/src/lbx.h
@@ -1,7 +1,7 @@
 #ifndef LBX_H_
 #define LBX_H_
 
-#include <stddef.h>
+#include <stdio.h>
 
 /* Errors */
 enum {
diff --git a/src/misc.c b/src/misc.c
new file mode 100644
index 0000000..b09e618
--- /dev/null
+++ b/src/misc.c
@@ -0,0 +1,45 @@
+#ifdef HAVE_CONFIG_H
+#	include "config.h"
+#endif
+
+#include <stdio.h>
+#include <errno.h>
+
+#include "misc.h"
+#include "lbx.h"
+
+int _lbx_fseek(FILE *f, long *current, size_t offset)
+{
+	static unsigned char oblivion[1024];
+	long dist;
+
+	if (*current < offset) {
+		dist = offset - *current;
+	} else if (*current > offset) {
+		dist = -(long)(*current - offset);
+	} else {
+		return 0;
+	}
+
+	if (fseek(f, dist, SEEK_CUR) == 0) {
+		*current += dist;
+	} else if (*current < offset) {
+		while (dist) {
+			size_t rc, amt = MIN(sizeof oblivion, dist);
+			rc = fread(oblivion, 1, amt, f);
+			*current += rc;
+			dist -= rc;
+			if (rc < amt) {
+				if (feof(f))
+					lbx_errno = LBX_EEOF;
+				else
+					lbx_errno = -errno;
+				return -1;
+			}
+		}
+	} else {
+		lbx_errno = -errno;
+		return -1;
+	}
+	return 0;
+}
diff --git a/src/misc.h b/src/misc.h
new file mode 100644
index 0000000..d7a7605
--- /dev/null
+++ b/src/misc.h
@@ -0,0 +1,16 @@
+#ifndef LBX_MISC_H_
+#define LBX_MISC_H_
+
+#include <stdio.h>
+
+#define MIN(a,b) (((a)<(b))?(a):(b))
+#define MAX(a,b) (((a)>(b))?(a):(b))
+
+/** _lbx_fseek()
+ * Seeks the specified file to the specified offset, given that the file is
+ * currently positioned at *current.  If the file does not support seeking,
+ * and offset > *current, perform the seek by reading (and discarding) data.
+ */
+int _lbx_fseek(FILE *f, long *current, size_t offset);
+
+#endif