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-rw-r--r--kernel/fs/tar.c306
1 files changed, 306 insertions, 0 deletions
diff --git a/kernel/fs/tar.c b/kernel/fs/tar.c
new file mode 100644
index 0000000..5f02c34
--- /dev/null
+++ b/kernel/fs/tar.c
@@ -0,0 +1,306 @@
+#include <comus/fs.h>
+#include <lib.h>
+#include <comus/tar.h>
+
+// the placements of these values mimics their placement in standard UStar
+struct tar_header {
+ char name[100]; // 0-99
+ char mode[8]; // 100-107
+ char ownerUID[8]; // 108-115
+ char groupUID[8]; // 116-123
+ char fileSize[12]; // 124-135
+ char lastMod[12]; // 136-147
+ char checksum[8]; // 148-155
+ char type_flag; // 156
+ char linked_name[100]; // 157-256
+ char magic[6]; // 257-262
+ char version[2]; // 263-264
+ char username[32]; // 265-296
+ char groupname[32]; // 297-328
+ char majorNum[8]; // 329-336
+ char minorNum[8]; // 337-344
+ char prefix[155]; // 345-499
+ char notUsed[12]; // 500-511
+};
+#define TAR_SIZE 512
+#define TMAGIC "ustar" /* ustar and a null */
+#define TMAGLEN 6
+#define TVERSION "00" /* 00 and no null */
+#define TVERSLEN 2
+#define ERROR_TAR 1
+#define NOERROR_TAR 0
+
+#define REGTYPE '0' /* regular file */
+#define DIRTYPE '5' /* directory */
+
+struct tar_file {
+ struct file file;
+ struct file_system *fs;
+ size_t len;
+ size_t offset;
+ size_t sect;
+};
+// read_tar_header reads what is in tar
+int read_tar_header(struct disk *disk, uint32_t sect, struct tar_header *hdr)
+{
+ if (disk_read(disk, sect * TAR_SIZE, TAR_SIZE, hdr) < TAR_SIZE) {
+ return ERROR_TAR;
+ }
+ if (memcmp(hdr->magic, TMAGIC, TMAGLEN) != 0 ||
+ memcmp(hdr->version, TVERSION, TVERSLEN) != 0) {
+ return ERROR_TAR;
+ }
+ return NOERROR_TAR;
+}
+
+/// @brief
+/// @param f the file to be read
+/// @param buffer the buffer that the content of the file is read into
+/// @param len
+/// @return
+int tar_read(struct file *f, void *buffer, size_t len)
+{
+ struct tar_file *tf = (struct tar_file *)f;
+ long size = MIN((tf->len - tf->offset), len);
+ if (tf->file.f_type != F_REG || size < 1) {
+ return ERROR_TAR;
+ }
+ size = disk_read(tf->fs->fs_disk, (tf->sect + 1) * TAR_SIZE + tf->offset,
+ size, buffer);
+ tf->offset += size;
+ return size;
+}
+//static int read_tar()
+// we are assuming that things are formatted correctly.
+int find_file(struct file_system *fs, const char *filepath, size_t *sect,
+ size_t *sect_return, struct tar_header *outHeader)
+{
+ //char *tempFilePath = filepath;
+ struct tar_header hdr;
+ size_t curr_sect;
+ if (sect == NULL) {
+ curr_sect = 0;
+ } else {
+ curr_sect = *sect;
+ }
+ while (1 == 1) {
+ if (read_tar_header(fs->fs_disk, curr_sect, &hdr) != 0) {
+ return ERROR_TAR;
+ }
+ if (memcmp(hdr.name, filepath, strlen(filepath) + 1) != 0) {
+ // didn't find it.
+
+ curr_sect +=
+ ((strtoull(hdr.fileSize, NULL, 8) + TAR_SIZE - 1) / TAR_SIZE) +
+ 1;
+ continue;
+ } else {
+ *outHeader = hdr;
+ *sect_return = curr_sect;
+ if (sect != NULL) {
+ sect += curr_sect;
+ }
+ return NOERROR_TAR;
+ }
+ }
+ return ERROR_TAR;
+}
+int find_file_redux(struct file_system *fs, const char *filepath, size_t *sect,
+ size_t *sect_return, struct tar_header *outHeader)
+{
+ struct tar_header hdr;
+ size_t curr_sect;
+ if (sect == NULL) {
+ curr_sect = 0;
+ } else {
+ curr_sect = *sect;
+ }
+ while (1 == 1) {
+ if (read_tar_header(fs->fs_disk, curr_sect, &hdr) != 0) {
+ return ERROR_TAR;
+ }
+ if (memcmp(hdr.name, filepath,
+ MIN(strlen(filepath), strlen(hdr.name))) != 0) {
+ // didn't find it.
+
+ curr_sect +=
+ ((strtoull(hdr.fileSize, NULL, 8) + TAR_SIZE - 1) / TAR_SIZE) +
+ 1;
+ continue;
+ } else {
+ *outHeader = hdr;
+ *sect_return = curr_sect;
+ if (sect != NULL) {
+ sect += curr_sect +
+ ((strtoull(hdr.fileSize, NULL, 8) + TAR_SIZE - 1) /
+ TAR_SIZE) +
+ 1;
+ }
+ return NOERROR_TAR;
+ }
+ }
+ return ERROR_TAR; // it should never actually reach here.
+}
+
+void tar_close(struct file *f)
+{
+ kfree(f);
+}
+
+int tar_seek(struct file *f, long int offsetAdd, int theSeek)
+{
+ struct tar_file *tf = (struct tar_file *)f;
+ if (theSeek == SEEK_SET) {
+ tf->offset = offsetAdd;
+ return tf->offset;
+ } else if (theSeek == SEEK_CUR) {
+ tf->offset = tf->offset + offsetAdd;
+ return tf->offset;
+ } else if (theSeek == SEEK_END) {
+ tf->offset = tf->len + offsetAdd;
+ return tf->offset;
+ } else {
+ return -1;
+ }
+}
+
+int tar_write(struct file *f, const void *buffer, size_t len)
+{
+ // tar doesn't do write lol. This is just here so there is something to send to write
+ (void)f;
+ (void)buffer;
+ (void)len;
+ return ERROR_TAR;
+}
+
+/*int tar_ents(struct file *f, struct dirent *d, size_t dIndex) {
+ struct tar_header hdr;
+ struct tar_header dir;
+ struct tar_file *tf = (struct tar_file*) f;
+ size_t sect = 0;
+ size_t sect_off = 0;
+ size_t curr_index = 0;
+ if(read_tar_header(tf->fs->fs_disk, sect, &hdr) != 0) {
+ return ERROR_TAR;
+ }
+ while(1 == 1) {
+ if(find_file_redux(tf->fs, dir.name, &sect_off, &sect, &dir) != 0) {
+ return ERROR_TAR;
+ }
+ if(curr_index < dIndex) {
+ curr_index += 1;
+ } else if(curr_index > dIndex) {
+ // something went seriously wrong
+ return ERROR_TAR;
+ } else {
+ d->d_namelen = strlen(hdr.name);
+ dir.type_flag = DIRTYPE;
+ d->d_offset = dIndex;
+ memcpy(d->d_name, hdr.name, d->d_namelen + 1);
+ return NOERROR_TAR;
+ }
+
+
+ }
+
+
+}*/
+
+int tar_ents(struct file *f, struct dirent *ent, size_t entry)
+{
+ struct tar_file *tf;
+ struct tar_header dir, hdr;
+ size_t sect;
+ size_t sect_off = 0;
+ size_t idx = 0;
+
+ tf = (struct tar_file *)f;
+ sect = 0;
+
+ if (tf->file.f_type != F_DIR)
+ return -1;
+
+ if (read_tar_header(tf->fs->fs_disk, sect, &dir)) {
+ return ERROR_TAR;
+ }
+
+ while (1) {
+ if (find_file_redux(tf->fs, dir.name, &sect_off, &sect, &hdr))
+ return ERROR_TAR;
+
+ if (idx != entry) {
+ idx++;
+ continue;
+ }
+
+ ent->d_offset = entry;
+ ent->d_namelen = strlen(hdr.name);
+ memcpy(ent->d_name, hdr.name, ent->d_namelen + 1);
+ return NOERROR_TAR;
+ }
+
+ return ERROR_TAR;
+}
+
+// opens up the tar file at fullpath, and puts it in out.
+int tar_open(struct file_system *fs, const char *fullpath, int flags,
+ struct file **out)
+{
+ struct tar_header hdr;
+ struct tar_file *newFile;
+ size_t sect_result;
+ find_file(fs, fullpath, NULL, &sect_result, &hdr);
+ if (flags != O_RDONLY) {
+ return ERROR_TAR;
+ }
+ newFile = kalloc(sizeof(struct tar_file));
+
+ newFile->file.f_type = F_REG;
+ newFile->fs = fs;
+ newFile->file.read = tar_read;
+ newFile->file.close = tar_close;
+ newFile->file.write = tar_write; // doesn't actually work;
+ newFile->file.ents = tar_ents;
+ newFile->file.seek = tar_seek;
+ newFile->offset = 0;
+ newFile->len = strtoull(hdr.fileSize, NULL, 8);
+ newFile->sect = sect_result;
+
+ *out = (struct file *)newFile;
+ return NOERROR_TAR;
+}
+
+// gets stats at the file at fullpath, putting them in out.
+int tar_stat(struct file_system *fs, const char *fullpath, struct stat *out)
+{
+ struct tar_header hdr;
+ size_t sect_result;
+ find_file(fs, fullpath, NULL, &sect_result, &hdr);
+ out->s_length = strtoull(hdr.fileSize, NULL, 8);
+ if (hdr.type_flag == REGTYPE) {
+ out->s_type = F_REG;
+ } else if (hdr.type_flag == DIRTYPE) {
+ out->s_type = F_DIR;
+ } else {
+ // wth
+ return ERROR_TAR;
+ }
+ return NOERROR_TAR;
+}
+
+// use tar for the filesystem.
+int tar_mount(struct file_system *fs)
+{
+ struct tar_header hdr;
+ // reads into hdr
+ if (read_tar_header(fs->fs_disk, 0, &hdr) == 0) {
+ fs->fs_name = "tar";
+ fs->open = tar_open;
+ fs->stat = tar_stat;
+ fs->fs_present = true;
+ return NOERROR_TAR;
+ }
+ return ERROR_TAR;
+}
+
+// no need to unmount, since mount just overrides whatever it was using previously. \ No newline at end of file
generated by cgit v1.2.3-freya (git 2.51.0) at 2025-09-23 23:04:10 +0000