From: Nick Bowler <nbowler@draconx.ca>
Date: Wed, 16 Sep 2009 01:05:32 +0000 (-0400)
Subject: libupkg: Parameterise I/O functions to allow custom streams.
X-Git-Url: https://git.draconx.ca/gitweb/upkg.git/commitdiff_plain/33c1796d255a720ad076160efd6859ca74d0792f

libupkg: Parameterise I/O functions to allow custom streams.
---

diff --git a/src/libupkg.c b/src/libupkg.c
index 503e3f5..ae48820 100644
--- a/src/libupkg.c
+++ b/src/libupkg.c
@@ -44,7 +44,8 @@ struct upkg_import {
 };
 
 struct upkg_private {
-	FILE *f;
+	const struct upkg_file_ops *fops;
+	void *f;
 
 	struct upkg_file *last_file;
 
@@ -56,6 +57,34 @@ struct upkg_private {
 	unsigned char guid[16];
 };
 
+/* Default I/O operations for ordinary files. */
+static size_t file_read(void *buf, size_t size, void *handle)
+{
+	return fread(buf, 1, size, handle);
+}
+
+static int file_seek(void *handle, long offset, int whence)
+{
+	return fseek(handle, offset, whence);
+}
+
+static long file_tell(void *handle)
+{
+	return ftell(handle);
+}
+
+static int file_eof(void *handle)
+{
+	return feof(handle);
+}
+
+const struct upkg_file_ops upkg_default_fops = {
+	.read = file_read,
+	.seek = file_seek,
+	.tell = file_tell,
+	.eof  = file_eof,
+};
+
 /*
  * Decode the compact index format from the upkg.  This format is fucked.
  * Stores the result in *val and returns the number of input bytes read (or 0
@@ -125,13 +154,14 @@ static struct upkg *init_upkg(unsigned char hdr[static UPKG_HDR_SIZE])
 
 static int pkg_init_guid(struct upkg *pkg)
 {
+	const struct upkg_file_ops *fops = pkg->priv->fops;
 	size_t rc;
 
 	if (pkg->version < 68) {
 		unsigned long heritage_count, heritage_offset;
 		unsigned char buf[8];
 
-		rc = fread(buf, 1, sizeof buf, pkg->priv->f);
+		rc = fops->read(buf, sizeof buf, pkg->priv->f);
 		if (rc < 8)
 			return -1;
 
@@ -140,11 +170,11 @@ static int pkg_init_guid(struct upkg *pkg)
 
 		if (heritage_count == 0)
 			return -1;
-		if (fseek(pkg->priv->f, heritage_offset, SEEK_SET) != 0)
+		if (fops->seek(pkg->priv->f, heritage_offset, SEEK_SET) != 0)
 			return -1;
 	}
 
-	rc = fread(pkg->guid, 1, 16, pkg->priv->f);
+	rc = fops->read(pkg->guid, 16, pkg->priv->f);
 	if (rc < 16)
 		return -1;
 
@@ -153,11 +183,14 @@ static int pkg_init_guid(struct upkg *pkg)
 
 static int pkg_init_names(struct upkg *pkg)
 {
+	const struct upkg_file_ops *fops = pkg->priv->fops;
+	void *f = pkg->priv->f;
+
 	size_t rc, len, nbuf = 0;
 	unsigned long index = 0;
 	unsigned char buf[512];
 
-	if (fseek(pkg->priv->f, pkg->priv->name_offset, SEEK_SET) != 0)
+	if (fops->seek(f, pkg->priv->name_offset, SEEK_SET) != 0)
 		return -1;
 
 	pkg->priv->names = malloc(pkg->name_count * sizeof *pkg->priv->names);
@@ -168,8 +201,8 @@ static int pkg_init_names(struct upkg *pkg)
 		struct upkg_name *name = &pkg->priv->names[index];
 
 		/* Read some data into buffer. */
-		if (!feof(pkg->priv->f)) {
-			rc = fread(buf+nbuf, 1, sizeof buf-nbuf, pkg->priv->f);
+		if (!fops->eof(pkg->priv->f)) {
+			rc = fops->read(buf+nbuf, sizeof buf-nbuf, f);
 			if (rc == 0 && nbuf == 0)
 				goto err;
 			nbuf += rc;
@@ -217,11 +250,14 @@ err:
 
 static int pkg_init_exports(struct upkg *pkg)
 {
+	const struct upkg_file_ops *fops = pkg->priv->fops;
+	void *f = pkg->priv->f;
+
 	size_t rc, len, nbuf = 0;
 	unsigned long index = 0;
 	unsigned char buf[512];
 
-	if (fseek(pkg->priv->f, pkg->priv->export_offset, SEEK_SET) != 0)
+	if (fops->seek(f, pkg->priv->export_offset, SEEK_SET) != 0)
 		return -1;
 
 	pkg->priv->exports = malloc(pkg->export_count * sizeof *pkg->priv->exports);
@@ -233,8 +269,8 @@ static int pkg_init_exports(struct upkg *pkg)
 		long tmp;
 
 		/* Read some data into buffer. */
-		if (!feof(pkg->priv->f)) {
-			rc = fread(buf+nbuf, 1, sizeof buf-nbuf, pkg->priv->f);
+		if (!fops->eof(pkg->priv->f)) {
+			rc = fops->read(buf+nbuf, sizeof buf-nbuf, f);
 			if (rc == 0 && nbuf == 0)
 				goto err;
 			nbuf += rc;
@@ -287,11 +323,14 @@ err:
 
 static int pkg_init_imports(struct upkg *pkg)
 {
+	const struct upkg_file_ops *fops = pkg->priv->fops;
+	void *f = pkg->priv->f;
+
 	size_t rc, len, nbuf = 0;
 	unsigned long index = 0;
 	unsigned char buf[512];
 
-	if (fseek(pkg->priv->f, pkg->priv->import_offset, SEEK_SET) != 0)
+	if (fops->seek(f, pkg->priv->import_offset, SEEK_SET) != 0)
 		return -1;
 
 	pkg->priv->imports = malloc(pkg->import_count * sizeof *pkg->priv->imports);
@@ -303,8 +342,8 @@ static int pkg_init_imports(struct upkg *pkg)
 		long tmp;
 
 		/* Read some data into buffer. */
-		if (!feof(pkg->priv->f)) {
-			rc = fread(buf+nbuf, 1, sizeof buf-nbuf, pkg->priv->f);
+		if (!fops->eof(pkg->priv->f)) {
+			rc = fops->read(buf+nbuf, sizeof buf-nbuf, f);
 			if (rc == 0 && nbuf == 0)
 				goto err;
 			nbuf += rc;
@@ -341,59 +380,72 @@ err:
 	return -1;
 }
 
-struct upkg *upkg_fopen(const char *path)
+struct upkg *upkg_open(void *f, const struct upkg_file_ops *fops)
 {
 	unsigned char hdr_buf[UPKG_HDR_SIZE];
 	struct upkg *pkg;
-	FILE *f;
 
-	if (!(f = fopen(path, "rb"))) {
+	if (fops->read(hdr_buf, sizeof hdr_buf, f) != sizeof hdr_buf) {
 		return NULL;
 	}
-	if (fread(hdr_buf, sizeof hdr_buf, 1, f) != 1) {
-		goto err1;
-	}
 	if (unpack_32_le(hdr_buf) != UPKG_HDR_MAGIC) {
-		goto err1;
+		return NULL;
 	}
 
 	/* Initialize package structure. */
 	pkg = init_upkg(hdr_buf);
 	if (!pkg) {
-		goto err1;
+		return NULL;
 	}
-	pkg->priv->f = f;
+	pkg->priv->fops = fops;
+	pkg->priv->f    = f;
 
 	if (pkg_init_guid(pkg) != 0) {
-		goto err2;
+		goto err1;
 	}
 
 	if (pkg_init_names(pkg) != 0) {
-		goto err2;
+		goto err1;
 	}
 
 	if (pkg_init_exports(pkg) != 0) {
-		goto err3;
+		goto err2;
 	}
 
 	if (pkg_init_imports(pkg) != 0) {
-		goto err4;
+		goto err3;
 	}
 
 	return pkg;
-err4:
-	free(pkg->priv->exports);
 err3:
+	free(pkg->priv->exports);
+err2:
 	for (unsigned i = 0; i < pkg->name_count; i++)
 		free(pkg->priv->names[i].name);
 	free(pkg->priv->names);
-err2:
-	free(pkg);
 err1:
-	fclose(f);
+	free(pkg);
 	return NULL;
 }
 
+struct upkg *upkg_fopen(const char *path)
+{
+	struct upkg *pkg;
+	FILE *f;
+
+	f = fopen(path, "rb");
+	if (!f) {
+		return NULL;
+	}
+
+	pkg = upkg_open(f, &upkg_default_fops);
+	if (!pkg) {
+		fclose(f);
+	}
+
+	return pkg;
+}
+
 int upkg_close(struct upkg *pkg)
 {
 	int rc = 0;
@@ -458,7 +510,7 @@ const char *upkg_export_class(struct upkg *pkg, unsigned long idx,
 
 	if (idx >= pkg->export_count)
 		return NULL;
-	
+
 	export = &pkg->priv->exports[idx];
 
 	/* ASSUMPTION: class references are always imports */
@@ -541,6 +593,7 @@ long upkg_export_tell(struct upkg_file *f)
 
 int upkg_export_seek(struct upkg_file *f, long offset, int whence)
 {
+	const struct upkg_file_ops *fops = f->pkg->priv->fops;
 	int rc = EOF;
 
 	switch (whence) {
@@ -549,14 +602,14 @@ int upkg_export_seek(struct upkg_file *f, long offset, int whence)
 	case SEEK_SET:
 		if (offset < 0 || offset > f->len)
 			return EOF;
-		rc = fseek(f->pkg->priv->f, f->base + offset, SEEK_SET);
+		rc = fops->seek(f->pkg->priv->f, f->base + offset, SEEK_SET);
 		break;
 	case SEEK_END:
 		offset = -offset;
 		if (offset < 0 || offset > f->len)
 			return EOF;
 		offset = f->len - offset;
-		rc = fseek(f->pkg->priv->f, f->base + offset, SEEK_SET);
+		rc = fops->seek(f->pkg->priv->f, f->base + offset, SEEK_SET);
 		break;
 	}
 
@@ -573,6 +626,7 @@ int upkg_export_seek(struct upkg_file *f, long offset, int whence)
 
 size_t upkg_export_read(struct upkg_file *f, void *buf, size_t n)
 {
+	const struct upkg_file_ops *fops = f->pkg->priv->fops;
 	size_t want = MIN(n, f->len - f->offset);
 	size_t rc;
 
@@ -581,14 +635,14 @@ size_t upkg_export_read(struct upkg_file *f, void *buf, size_t n)
 	}
 
 	if (f != f->pkg->priv->last_file) {
-		if (fseek(f->pkg->priv->f, f->base + f->offset, SEEK_SET))
+		if (fops->seek(f->pkg->priv->f, f->base + f->offset, SEEK_SET))
 			return 0;
 	}
 
-	rc = fread(buf, 1, want, f->pkg->priv->f);
+	rc = fops->read(buf, want, f->pkg->priv->f);
 	f->offset += rc;
 
-	if (want < n || (rc < want && feof(f->pkg->priv->f)))
+	if (want < n || (rc < want && fops->eof(f->pkg->priv->f)))
 		f->eof = 1;
 	return rc;
 }
diff --git a/src/upkg.h b/src/upkg.h
index 7565b32..9fc8003 100644
--- a/src/upkg.h
+++ b/src/upkg.h
@@ -62,6 +62,13 @@
 #define UPKG_HDR_MAGIC 0x9e2a83c1
 #define UPKG_HDR_SIZE  36
 
+struct upkg_file_ops {
+	size_t (*read)(void *buf, size_t size, void *handle);
+	int    (*seek)(void *handle, long offset, int whence);
+	long   (*tell)(void *handle);
+	int    (*eof) (void *handle);
+};
+
 struct upkg {
 	unsigned version, license;
 	unsigned char guid[16];
@@ -81,6 +88,10 @@ struct upkg_file {
 	unsigned long base, offset, len;
 };
 
+/* Default I/O operations for ordinary files. */
+extern const struct upkg_file_ops upkg_default_fops;
+
+struct upkg *upkg_open(void *handle, const struct upkg_file_ops *fops);
 struct upkg *upkg_fopen(const char *path);
 int upkg_close(struct upkg *pkg);