Move the source files to a src directory

1 files changed, 376 insertions, 0 deletions

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));
+    }
+}