Add iso_file_src default implementation.

This will be the base class for file content writting, with support for 
on-the-file file modification, useful for things like compression or 
encryption.

Makefile.am

@@ -32,6 +32,8 @@ libisofs_libisofs_la_SOURCES = \
 	libisofs/hash.c  \
 	libisofs/file.h \
 	libisofs/file.c  \
+	libisofs/file_src.h \
+	libisofs/file_src.c  \
 	libisofs/eltorito.h \
 	libisofs/eltorito.c \
 	libisofs/data_source.c \

libisofs/file_src.c

@@ -0,0 +1,163 @@
+#include <stdlib.h>       
+#include <stdio.h>       
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <assert.h>
+#include <string.h>
+#include <limits.h>
+
+#include "file_src.h"
+#include "messages.h"
+
+#define BLOCK_SIZE 2048
+
+struct local_file_data {
+	int fd; /* the file descriptor, once the file is opened */
+	off_t size; /* file size */
+	off_t bytes_read; /* bytes already read from file */
+	int error;
+	char *path; /* path of the file on local filesystem */
+};
+
+static
+int lf_open(struct iso_file_src *src)
+{
+	struct local_file_data *data;
+	assert(src);
+	
+	data = (struct local_file_data*) src->data;
+	
+	assert(data->fd == -1);
+	
+	data->fd = open(data->path, O_RDONLY);
+	data->bytes_read = (off_t) 0;
+	data->error = 0;
+	return (data->fd != -1 ? 1 : 0);
+}
+
+static
+void lf_close(struct iso_file_src *src)
+{
+	struct local_file_data *data;
+	assert(src);
+	
+	data = (struct local_file_data*) src->data;
+	assert(data->fd != -1);
+	
+	close(data->fd);
+	data->fd = -1;
+}
+
+static
+int lf_read_block(struct iso_file_src *src, unsigned char *buffer)
+{
+	ssize_t bytes;
+	struct local_file_data *data;
+	assert(src);
+	assert(buffer);
+	
+	data = (struct local_file_data*) src->data;
+	assert(data->fd != -1);
+	
+	if (data->bytes_read >= data->size) {
+		return 0;
+	}
+	
+	if (data->error) {
+		memset(buffer, 0, BLOCK_SIZE);
+		data->bytes_read += BLOCK_SIZE;
+		return -2;
+	}
+	
+	bytes = 0;
+	
+	do {
+		ssize_t result;
+		result = read(data->fd, buffer + bytes, BLOCK_SIZE - bytes);
+		if (result < 0) {
+			char msg[PATH_MAX + 32];
+			sprintf(msg, "Problem reading from %s", data->path);
+			iso_msg_sorry(LIBISO_CANT_READ_FILE, msg);
+			
+			/* fill buffer with 0s and return */ 
+			memset(buffer + bytes, 0, BLOCK_SIZE - bytes);
+			data->bytes_read += BLOCK_SIZE;
+			return -1;
+		}
+		if (!result)
+			break;
+		bytes += result;	
+	} while (bytes < BLOCK_SIZE);
+	
+	if (bytes < BLOCK_SIZE) {
+		/* eof */
+		memset(buffer + bytes, 0, BLOCK_SIZE - bytes);
+	}
+	
+	data->bytes_read += (off_t) bytes;
+	if (data->bytes_read >= data->size) {
+		return 0;
+	} else {
+		return 1;
+	}
+}
+
+static
+off_t lf_get_size(struct iso_file_src *src)
+{
+	struct local_file_data *data;
+	assert(src);
+	
+	data = (struct local_file_data*) src->data;
+	return data->size;
+}
+
+static
+void lf_free_data(struct iso_file_src *src)
+{
+	free(src->data);
+}
+
+struct iso_file_src* 
+iso_file_src_from_path(const char *path)
+{
+	struct stat info;
+	struct iso_file_src *src;
+	struct local_file_data *data;
+	
+	assert(path);
+	
+	if (lstat(path, &info) < 0) {
+		iso_msg_fatal(LIBISO_FILE_DOESNT_EXIST, "File doesn't exist");
+		return NULL;
+	}
+	if (access(path, R_OK) < 0) {
+		iso_msg_fatal(LIBISO_FILE_NO_READ_ACCESS, "No read access");
+		return NULL;
+	}
+	
+	data = malloc(sizeof(struct local_file_data));
+	if (!data)
+		return NULL;
+	
+	src = malloc(sizeof(struct iso_file_src));	
+	if (!src) {
+		free(data);
+		return NULL;
+	}
+	
+	data->fd = -1;
+	data->path = strdup(path);
+	data->size = info.st_size;
+	
+	src->open = lf_open;
+	src->close = lf_close;
+	src->read_block = lf_read_block;
+	src->get_size = lf_get_size;
+	src->free_data = lf_free_data;
+	
+	src->data = data;
+	return src;
+}

libisofs/file_src.h

@@ -0,0 +1,82 @@
+
+/*
+ * Class for reading data from files, with base implementations
+ * for reading local filesystem files and previous session files.
+ * 
+ * TODO this is kept private for now, it can be useful to make that
+ * public later.
+ */
+
+#ifndef FILE_SRC_H_
+#define FILE_SRC_H_
+
+#include <sys/types.h>
+
+struct iso_file_src {
+	
+	/**
+	 * Opens the file. 
+	 * This should be called before any call to read_block().
+	 * @return 1 on success, <= 0 on error
+	 */
+	int (*open)(struct iso_file_src *src);
+	
+	/**
+	 * Close the file.
+	 * This should be called when the iso_file_src is no more needed.
+	 */
+	void (*close)(struct iso_file_src *src);
+	
+	/** 
+	 * Read data from the file in 2048 bytes chunks.
+	 * 
+	 * A pointer to the contents of the file will be updated, in such a way
+	 * that each time this function is called, new data is read to the buffer.
+	 * It behaves in the same way as usual read(2) call this way.
+	 * 
+	 * This always reads 2048 bytes, unless an EOF is found, or we reach the
+	 * size previously returned by get_size(). In this case, the buffer is 
+	 * completed with 0s.
+	 * 
+	 * @param buffer Buffer where the data will be written. Its size must
+	 *               be at least 2048 bytes.
+	 * @return
+	 * 		1 if file contains more data. If we reach EOF before the expected
+	 *      size, this keeps returning 1, and next blocks are filled with 0s.
+	 * 	    0 when we reach the expected size, that in normal usage is also EOF
+	 *      on file.
+	 *      < 0 on error. If such case, next calls to read_block will keep
+	 *      returning < 0 until we reach the expected size, filling blocks with
+	 *      0s.
+	 */
+	int (*read_block)(struct iso_file_src *src, unsigned char *buffer);
+
+	/** 
+	 * Get the size in bytes of the file. 
+	 * 
+	 * This is set when the iso_file_src is created, and should not change. If
+	 * the actual file size changes, it will be truncated or padding with 0s
+	 * when the block is read
+	 */
+	off_t (*get_size)(struct iso_file_src *);
+
+	/** Clean up the source specific data */
+	void (*free_data)(struct iso_file_src *);
+
+	/** Source specific data */
+	void *data;
+	
+};
+
+/**
+ * Get a iso_file_src() for reading from a local filesystem file.
+ */
+struct iso_file_src* iso_file_src_from_path(const char *path);
+
+/**
+ * close and free a iso_file_src
+ */
+void iso_file_src_free(struct iso_file_src *src);
+
+
+#endif /*FILE_SRC_H_*/

libisofs/libiso_msgs.h

@@ -385,6 +385,8 @@ Range "vreixo"              :  0x00030000 to 0x0003ffff
  General:
  0x00031001 (SORRY,HIGH)    = Can't read file (ignored)
  0x00031002 (FATAL,HIGH)    = Can't read file (operation canceled)
+ 0x00031003 (FATAL,HIGH)    = File doesn't exist
+ 0x00031004 (FATAL,HIGH)    = Read access denied
 
  Image reading:
  0x00031000 (FATAL,HIGH)    = Unsupported ISO-9660 image

libisofs/messages.h

@@ -11,6 +11,10 @@
 #define LIBISO_CANT_READ_FILE		0x00031001
 /** Can't read file (operation canceled) */
 #define LIBISO_FILE_READ_ERROR		0x00031002
+/** File doesn't exist */
+#define LIBISO_FILE_DOESNT_EXIST	0x00031003
+/** Read access denied */
+#define LIBISO_FILE_NO_READ_ACCESS	0x00031004
 
 /** Unsupported image feature */
 #define LIBISO_IMG_UNSUPPORTED		0x00031000