Move the source files to a src directory

10 files changed, 651 insertions, 0 deletions

diff --git a/src/Makefile b/src/Makefile
new file mode 100644
index 0000000..8b24b35
--- /dev/null
+++ b/src/Makefile
@@ -0,0 +1,19 @@
+CC=gcc
+CFLAGS=-Wall
+
+SOURCES=*.c
+HEADERS=*.h
+
+all: $(PROGRAM_NAME)
+
+$(PROGRAM_NAME): $(SOURCES) $(HEADERS) program_info.h
+	$(CC) $(CFLAGS) -o $(PROGRAM_NAME) $(SOURCES)
+
+program_info.h:
+	echo "#define PROGRAM_NAME_STR \"$(PROGRAM_NAME)\"" >program_info.h
+	echo "#define PROGRAM_VERSION_STR \"$(PROGRAM_VERSION)\"" >>program_info.h
+
+.PHONY: clean
+
+clean:
+	rm -f *.o *~ $(PROGRAM_NAME) program_info.h
diff --git a/src/file.c b/src/file.c
new file mode 100644
index 0000000..c6823b9
--- /dev/null
+++ b/src/file.c
@@ -0,0 +1,23 @@
+#include <errno.h>
+#include <string.h>
+
+#include "file.h"
+#include "print.h"
+
+long
+file_size(FILE *const file)
+{
+    fpos_t p;
+
+    if ((fgetpos(file, &p) != 0) || (fseek(file, 0L, SEEK_END) != 0)) {
+        return -1;
+    }
+
+    const long size = ftell(file);
+
+    if (fsetpos(file, &p) != 0) {
+        return -1;
+    }
+
+    return size;
+}
diff --git a/src/file.h b/src/file.h
new file mode 100644
index 0000000..d62b1ba
--- /dev/null
+++ b/src/file.h
@@ -0,0 +1,8 @@
+#ifndef FILE_H
+#define FILE_H
+
+#include <stdio.h>
+
+long file_size(FILE *const file);
+
+#endif /* FILE_H */
diff --git a/src/main.c b/src/main.c
new file mode 100644
index 0000000..ea94921
--- /dev/null
+++ b/src/main.c
@@ -0,0 +1,376 @@
+#include <endian.h>
+#include <errno.h>
+#include <inttypes.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "file.h"
+#include "options.h"
+#include "print.h"
+#include "resources.h"
+
+/* This header file is automatically generated at build time from the Makefile
+ */
+#include "program_info.h"
+
+void
+usage(int exit_code)
+{
+    printf("Usage: %s [-s SECTOR_SIZE] [-b BUFFER_SIZE] [INFILE] REFFILE "
+           "OUTFILE\n",
+           PROGRAM_NAME_STR);
+    exit(exit_code);
+}
+
+void
+clean_exit(resources_t *const res, int exit_code)
+{
+    resources_free(res);
+    exit(exit_code);
+}
+
+int
+open_files(const options_t *const opts, resources_t *const res,
+           bool is_action_backup)
+{
+    /* Open the input file */
+    if ((opts->in_file_path != NULL) &&
+        ((res->in_file = fopen(opts->in_file_path, "r")) == NULL)) {
+        print_error("cannot open input file: %s", strerror(errno));
+        return 1;
+    }
+
+    /* Open the reference file */
+    if ((res->ref_file = fopen(opts->ref_file_path, "r")) == NULL) {
+        print_error("cannot open reference file: %s", strerror(errno));
+        return 1;
+    }
+
+    /* Open the output file
+     *
+     * When restoring, the file must be opened for writing and not
+     * truncated
+     */
+    char out_mode[] = "r+";
+
+    if (is_action_backup) {
+        /* When backing up, the output file is truncated to hold the
+         * new data
+         */
+        out_mode[0] = 'w';
+        out_mode[1] = '\0';
+    }
+
+    if ((res->out_file = fopen(opts->out_file_path, out_mode)) == NULL) {
+        print_error("cannot open output file: %s", strerror(errno));
+        return 1;
+    }
+
+    return 0;
+}
+
+bool
+is_reference_file_valid(resources_t *const res, uint32_t sector_size)
+{
+    const long ref_size = file_size(res->ref_file);
+
+    if (ref_size < 0) {
+        print_error("cannot get size of reference file: %s", strerror(errno));
+        return false;
+    } else if (ref_size == 0) {
+        print_error("reference file is empty");
+        return false;
+    } else if ((ref_size % (sizeof(uint64_t) + sector_size)) != 0) {
+        /* The reference file must hold equally sized sectors and the
+         * offset of each of them
+         */
+        print_error(
+            "reference file has size that cannot contain valid diff data");
+        return false;
+    }
+
+    const long out_size = file_size(res->out_file);
+
+    if (out_size < 0) {
+        print_error("cannot get size of output file: %s", strerror(errno));
+        return 1;
+    }
+
+    uint64_t ref_offset = 0;
+    uint64_t prev_out_offset;
+
+    /* Scan the reference file and check  */
+    for (;;) {
+        uint64_t out_offset;
+        /* Read the next offset */
+        const size_t ref_read =
+            fread(&out_offset, sizeof(out_offset), 1U, res->ref_file);
+        out_offset = le64toh(out_offset);
+
+        if (feof(res->ref_file)) {
+            break;
+        } else if ((ref_read != 1U) || ferror(res->ref_file)) {
+            print_error("cannot read from reference file: %s", strerror(errno));
+            return false;
+        } else if (((ref_offset != 0) && (out_offset <= prev_out_offset)) ||
+                   ((out_offset + sector_size) > out_size)) {
+            /* The offset must be higher than the previous one and it
+             * must point into the file
+             */
+            print_error("reference file is not valid");
+            return false;
+        } else if (fseek(res->ref_file, sector_size, SEEK_CUR) != 0) {
+            print_error("cannot seek in reference file: %s", strerror(errno));
+            return false;
+        }
+
+        prev_out_offset = out_offset;
+    }
+
+    if (ftell(res->ref_file) != ref_size) {
+        /* The reference file must be read completely */
+        print_error("reference file is not valid");
+        return false;
+    } else if (fseek(res->ref_file, 0L, SEEK_SET) != 0) {
+        /* The file must be prepared for the restoring */
+        print_error("cannot seek in reference file: %s", strerror(errno));
+        return false;
+    }
+
+    return true;
+}
+
+int
+diff_backup(const options_t *const opts, resources_t *const res)
+{
+    const long in_size = file_size(res->in_file);
+
+    if (in_size < 0) {
+        print_error("cannot get size of input file: %s", strerror(errno));
+        return 1;
+    }
+
+    const long ref_size = file_size(res->ref_file);
+
+    if (ref_size < 0) {
+        print_error("cannot get size of reference file: %s", strerror(errno));
+        return 1;
+    }
+
+    /* Check sizes of the input file and the reference file */
+    if (in_size != ref_size) {
+        print_error("input file and reference file differ in size");
+        return 1;
+    } else if ((in_size % opts->sector_size) != 0) {
+        print_error(
+            "size of input file and reference file is not multiple of" PRIu32,
+            opts->sector_size);
+        return 1;
+    }
+
+    /* Allocate the buffers */
+    /* The output buffer contains also the offsets */
+    const size_t out_buffer_size =
+        ((opts->buffer_size / opts->sector_size) * sizeof(uint64_t)) +
+        opts->buffer_size;
+
+    if ((res->in_buffer = (char *)malloc(opts->buffer_size)) == NULL) {
+        print_error("cannot allocate buffer for input file data");
+        return 1;
+    } else if ((res->ref_buffer = (char *)malloc(opts->buffer_size)) == NULL) {
+        print_error("cannot allocate buffer for reference file data");
+        return 1;
+    } else if ((res->out_buffer = (char *)malloc(out_buffer_size)) == NULL) {
+        print_error("cannot allocate buffer for output file data");
+        return 1;
+    }
+
+    size_t out_buffer_index = 0;
+    uint64_t offset = 0;
+
+    for (;;) {
+        /* Read the sectors from the input file to the buffer */
+        const size_t in_read =
+            fread(res->in_buffer, 1U, opts->buffer_size, res->in_file);
+
+        if ((in_read % opts->sector_size) != 0) {
+            print_error(
+                "data read from input file is not multiple of sector size");
+            return 1;
+        } else if (ferror(res->in_file)) {
+            print_error("cannot read from input file: %s", strerror(errno));
+            return 1;
+        }
+
+        /* Read sectors from the reference file to the buffer */
+        const size_t ref_read =
+            fread(res->ref_buffer, 1U, opts->buffer_size, res->ref_file);
+
+        if ((ref_read % opts->sector_size) != 0) {
+            print_error(
+                "data read from reference file is not multiple of sector size");
+            return 1;
+        } else if (ferror(res->ref_file)) {
+            print_error("%s", strerror(errno));
+            return 1;
+        }
+
+        if (in_read != ref_read) {
+            print_error(
+                "data read from input file and reference file differ in size");
+            return 1;
+        }
+
+        /* Process sectors in the buffer */
+        for (size_t i = 0; i < in_read; i += opts->sector_size) {
+            /* Compare the sectors  */
+            int changed = 0;
+            const size_t j_end = i + opts->sector_size;
+            for (size_t j = i; j < j_end; ++j) {
+                if (res->in_buffer[j] != res->ref_buffer[j]) {
+                    changed = 1;
+                    break;
+                }
+            }
+
+            if (changed) {
+                /* Write changed sector */
+                if (out_buffer_index >= out_buffer_size) {
+                    /* The output buffer is full. Write it to the
+                     * output file.
+                     */
+                    const size_t x = fwrite(res->out_buffer, 1U,
+                                            out_buffer_index, res->out_file);
+
+                    if (x != out_buffer_index) {
+                        print_error("cannot write to output file: %s",
+                                    strerror(errno));
+                        return 1;
+                    }
+
+                    out_buffer_index = 0;
+                }
+
+                const uint64_t o = htole64(offset);
+
+                memcpy(res->out_buffer + out_buffer_index, (void *)&o,
+                       sizeof(o));
+                memcpy(res->out_buffer + out_buffer_index, &(res->in_buffer[i]),
+                       opts->sector_size);
+                out_buffer_index += sizeof(o) + opts->sector_size;
+            }
+
+            offset += opts->sector_size;
+        }
+
+        if (feof(res->in_file)) {
+            break;
+        }
+    }
+
+    /* Write out the output buffer */
+    if (out_buffer_index >= 0) {
+        const size_t x =
+            fwrite(res->out_buffer, 1U, out_buffer_index, res->out_file);
+
+        if (x != out_buffer_index) {
+            print_error("cannot write to output file: %s", strerror(errno));
+            return 1;
+        }
+    }
+
+    return 0;
+}
+
+int
+diff_restore(const options_t *const opts, resources_t *const res)
+{
+    /* Check validity of the reference file */
+    if (!is_reference_file_valid(res, opts->sector_size)) {
+        return 1;
+    }
+
+    const long ref_size = file_size(res->ref_file);
+
+    if (ref_size < 0) {
+        print_error("cannot get size of reference file: %s", strerror(errno));
+        return 1;
+    }
+
+    /* Allocate the buffer for data from the reference file */
+    /* The reference buffer contains also the offsets */
+    const size_t ref_buffer_size =
+        ((opts->buffer_size / opts->sector_size) * sizeof(uint64_t)) +
+        opts->buffer_size;
+
+    if ((res->ref_buffer = (char *)malloc(ref_buffer_size)) == NULL) {
+        print_error("cannot allocate buffer for reference file data");
+        return 1;
+    }
+
+    /* Restore data from the differential image */
+    uint64_t out_offset;
+
+    for (;;) {
+        /* Read data of the offset and the next sector */
+        const size_t ref_read =
+            fread(res->ref_buffer, ref_buffer_size, 1U, res->ref_file);
+
+        if (feof(res->ref_file)) {
+            break;
+        } else if ((ref_read != 1U) || ferror(res->ref_file)) {
+            print_error("cannot read from reference file: %s", strerror(errno));
+            return 1;
+        }
+
+        /* Get offset */
+        out_offset = le64toh(*((uint64_t *)res->ref_buffer));
+
+        if (fseek(res->out_file, out_offset, SEEK_SET) != 0) {
+            print_error("cannot seek in output file: %s", strerror(errno));
+            return 1;
+        }
+
+        /* Write the sector data to the output file */
+        const size_t out_written = fwrite(res->ref_buffer + sizeof(out_offset),
+                                          opts->sector_size, 1U, res->out_file);
+
+        if (out_written != 1U) {
+            print_error("cannot write to output file: %s", strerror(errno));
+            return 1;
+        }
+    }
+
+    /* The reference file must be read completely */
+    if (ftell(res->ref_file) != ref_size) {
+        print_error("reference file is not valid");
+        return 1;
+    }
+
+    return 0;
+}
+
+int
+main(int argc, char **argv)
+{
+    options_t opts;
+
+    if (options_parse(argc, argv, &opts) || opts.help) {
+        usage(1);
+    }
+
+    const bool is_action_backup = (opts.in_file_path != NULL);
+    resources_t res;
+
+    resources_init(&res);
+
+    if (open_files(&opts, &res, is_action_backup) != 0) {
+        clean_exit(&res, 1);
+    } else if (is_action_backup) {
+        clean_exit(&res, diff_backup(&opts, &res));
+    } else {
+        clean_exit(&res, diff_restore(&opts, &res));
+    }
+}
diff --git a/src/options.c b/src/options.c
new file mode 100644
index 0000000..2017ba5
--- /dev/null
+++ b/src/options.c
@@ -0,0 +1,118 @@
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "options.h"
+#include "print.h"
+
+#define OPTIONS_DEFAULT_SECTOR_SIZE 512
+#define OPTIONS_DEFAULT_BUFFER_SIZE (4 * 1024 * 1024)
+
+void options_init(options_t *const opts);
+int options_parse_unsigned(const char *const arg, uint32_t *const value);
+
+int
+options_parse(int argc, char **argv, options_t *const opts)
+{
+    options_init(opts);
+
+    int ch;
+    char *arg_sector_size = NULL;
+    char *arg_buffer_size = NULL;
+
+    while ((ch = getopt(argc, argv, ":s:b:h")) != -1) {
+        switch (ch) {
+        case 's':
+            arg_sector_size = optarg;
+            break;
+
+        case 'b':
+            arg_buffer_size = optarg;
+            break;
+
+        case 'h':
+            opts->help = true;
+            break;
+
+        case ':':
+            print_error("missing argument for option '-%c'", optopt);
+            return 1;
+
+        default:
+            print_error("unknown option '-%c'", optopt);
+            return 1;
+        }
+    }
+
+    argc -= optind;
+    argv += optind;
+
+    if (opts->help) {
+        return 0;
+    } else if (argc < 2) {
+        print_error("missing arguments");
+        return 1;
+    } else if (argc > 3) {
+        print_error("too many arguments");
+        return 1;
+    }
+
+    /* Convert numbers in the arguments */
+    if ((arg_sector_size != NULL) &&
+        options_parse_unsigned(arg_sector_size, &(opts->sector_size))) {
+        print_error("incorrect sector size");
+        return 1;
+    } else if ((arg_buffer_size != NULL) &&
+               options_parse_unsigned(arg_buffer_size, &(opts->buffer_size))) {
+        print_error("incorrect buffer size");
+        return 1;
+    } else if (opts->sector_size == 0) {
+        print_error("sector size cannot be 0");
+        return 1;
+    } else if (opts->buffer_size == 0) {
+        print_error("buffer size cannot be 0");
+        return 1;
+    } else if (opts->sector_size > opts->buffer_size) {
+        print_error("sector size cannot larger than buffer size");
+        return 1;
+    } else if ((opts->buffer_size % opts->sector_size) != 0) {
+        print_error("buffer size is not multiple of sector size");
+        return 1;
+    }
+
+    /* Pick the file paths */
+    int last_path_index = argc - 1;
+    opts->out_file_path = argv[last_path_index--];
+    opts->ref_file_path = argv[last_path_index--];
+    if (last_path_index >= 0) {
+        opts->in_file_path = argv[last_path_index];
+    }
+
+    return 0;
+}
+
+void
+options_init(options_t *const opts)
+{
+    opts->help = false;
+    opts->sector_size = OPTIONS_DEFAULT_SECTOR_SIZE;
+    opts->buffer_size = OPTIONS_DEFAULT_BUFFER_SIZE;
+
+    opts->in_file_path = NULL;
+    opts->ref_file_path = NULL;
+    opts->out_file_path = NULL;
+}
+
+int
+options_parse_unsigned(const char *const arg, uint32_t *const value)
+{
+    char *end;
+
+    errno = 0;
+
+    *value = strtoul(arg, &end, 0);
+
+    return ((*end != '\0') || (errno != 0)) ? -1 : 0;
+}
diff --git a/src/options.h b/src/options.h
new file mode 100644
index 0000000..71259aa
--- /dev/null
+++ b/src/options.h
@@ -0,0 +1,19 @@
+#ifndef OPTIONS_H
+#define OPTIONS_H
+
+#include <stdbool.h>
+#include <stdint.h>
+
+typedef struct {
+    bool help;
+    uint32_t sector_size;
+    uint32_t buffer_size;
+
+    const char *in_file_path;
+    const char *ref_file_path;
+    const char *out_file_path;
+} options_t;
+
+int options_parse(int argc, char **argv, options_t *const opts);
+
+#endif /* OPTIONS_H */
diff --git a/src/print.c b/src/print.c
new file mode 100644
index 0000000..824f818
--- /dev/null
+++ b/src/print.c
@@ -0,0 +1,21 @@
+#include <stdarg.h>
+#include <stdio.h>
+
+#include "print.h"
+
+#define PRINT_ERROR_PREFIX "ERROR: "
+#define PRINT_ERROR_SUFFIX "\n"
+
+void
+print_error(const char *const format, ...)
+{
+    fprintf(stderr, PRINT_ERROR_PREFIX);
+
+    va_list args;
+
+    va_start(args, format);
+    vfprintf(stderr, format, args);
+    va_end(args);
+
+    fprintf(stderr, PRINT_ERROR_SUFFIX);
+}
diff --git a/src/print.h b/src/print.h
new file mode 100644
index 0000000..7992087
--- /dev/null
+++ b/src/print.h
@@ -0,0 +1,6 @@
+#ifndef PRINT_H
+#define PRINT_H
+
+void print_error(const char *const format, ...);
+
+#endif /* PRINT_H */
diff --git a/src/resources.c b/src/resources.c
new file mode 100644
index 0000000..3eebd1c
--- /dev/null
+++ b/src/resources.c
@@ -0,0 +1,44 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "resources.h"
+
+void
+resources_init(resources_t *const res)
+{
+    res->in_file = NULL;
+    res->ref_file = NULL;
+    res->out_file = NULL;
+    res->in_buffer = NULL;
+    res->ref_buffer = NULL;
+    res->out_buffer = NULL;
+}
+
+void
+resources_free(resources_t *const res)
+{
+    if (res->in_file != NULL) {
+        fclose(res->in_file);
+        res->in_file = NULL;
+    }
+    if (res->ref_file != NULL) {
+        fclose(res->ref_file);
+        res->ref_file = NULL;
+    }
+    if (res->out_file != NULL) {
+        fclose(res->out_file);
+        res->out_file = NULL;
+    }
+    if (res->in_buffer != NULL) {
+        free(res->in_buffer);
+        res->in_buffer = NULL;
+    }
+    if (res->ref_buffer != NULL) {
+        free(res->ref_buffer);
+        res->ref_buffer = NULL;
+    }
+    if (res->out_buffer != NULL) {
+        free(res->out_buffer);
+        res->out_buffer = NULL;
+    }
+}
diff --git a/src/resources.h b/src/resources.h
new file mode 100644
index 0000000..0cf9777
--- /dev/null
+++ b/src/resources.h
@@ -0,0 +1,17 @@
+#ifndef RESOURCES_H
+#define RESOURCES_H
+
+typedef struct {
+    FILE *in_file;
+    FILE *ref_file;
+    FILE *out_file;
+
+    char *in_buffer;
+    char *ref_buffer;
+    char *out_buffer;
+} resources_t;
+
+void resources_init(resources_t *const res);
+void resources_free(resources_t *const res);
+
+#endif /* RESOURCES_H */