Initial commit of block device interface and emulated block device

2017-02-25 14:31:14 -06:00
parent b113bba3ae
commit 02156cb47d
7 changed files with 471 additions and 43 deletions
@@ -0,0 +1,197 @@
+/*
+ * Simple config parser
+ *
+ * Copyright (c) 2017 Christopher Haster
+ * Distributed under the MIT license
+ */
+#include "emubd/lfs_cfg.h"
+
+#include <stdlib.h>
+#include <errno.h>
+#include <string.h>
+#include <stdio.h>
+
+
+static int lfs_cfg_buffer(lfs_cfg_t *cfg, char c) {
+    // Amortize double
+    if (cfg->blen == cfg->bsize) {
+        size_t nsize = cfg->bsize * 2;
+        char *nbuf = malloc(nsize);
+        if (!nbuf) {
+            return -ENOMEM;
+        }
+
+        memcpy(nbuf, cfg->buf, cfg->bsize);
+        free(cfg->buf);
+        cfg->buf = nbuf;
+        cfg->bsize = nsize;
+    }
+
+    cfg->buf[cfg->blen] = c;
+    cfg->blen += 1;
+    return 0;
+}
+
+static int lfs_cfg_attr(lfs_cfg_t *cfg, unsigned key, unsigned val) {
+    // Amortize double
+    if (cfg->len == cfg->size) {
+        size_t nsize = cfg->size * 2;
+        struct lfs_cfg_attr *nattrs = malloc(nsize*sizeof(struct lfs_cfg_attr));
+        if (!nattrs) {
+            return -ENOMEM;
+        }
+
+        memcpy(nattrs, cfg->attrs, cfg->size*sizeof(struct lfs_cfg_attr));
+        free(cfg->attrs);
+        cfg->attrs = nattrs;
+        cfg->size = nsize;
+    }
+
+    // Keep attrs sorted for binary search
+    unsigned i = 0;
+    while (i < cfg->len &&
+            strcmp(&cfg->buf[key],
+                &cfg->buf[cfg->attrs[i].key]) > 0) {
+        i += 1;
+    }
+
+    memmove(&cfg->attrs[i+1], &cfg->attrs[i],
+        (cfg->size - i)*sizeof(struct lfs_cfg_attr));
+    cfg->attrs[i].key = key;
+    cfg->attrs[i].val = val;
+    cfg->len += 1;
+    return 0;
+}
+
+static bool lfs_cfg_match(FILE *f, const char *matches) {
+    char c = getc(f);
+    ungetc(c, f);
+
+    for (int i = 0; matches[i]; i++) {
+        if (c == matches[i]) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+int lfs_cfg_create(lfs_cfg_t *cfg, const char *filename) {
+    // start with some initial space
+    cfg->len = 0;
+    cfg->size = 4;
+    cfg->attrs = malloc(cfg->size*sizeof(struct lfs_cfg_attr));
+
+    cfg->blen = 0;
+    cfg->bsize = 16;
+    cfg->buf = malloc(cfg->size);
+
+    FILE *f = fopen(filename, "r");
+    if (!f) {
+        return -errno;
+    }
+
+    while (!feof(f)) {
+        int err;
+
+        while (lfs_cfg_match(f, " \t\v\f")) {
+            fgetc(f);
+        }
+
+        if (!lfs_cfg_match(f, "#\r\n")) {
+            unsigned key = cfg->blen;
+            while (!lfs_cfg_match(f, " \t\v\f:#") && !feof(f)) {
+                if ((err = lfs_cfg_buffer(cfg, fgetc(f)))) {
+                    return err;
+                }
+            }
+            if ((err = lfs_cfg_buffer(cfg, 0))) {
+                return err;
+            }
+
+            while (lfs_cfg_match(f, " \t\v\f")) {
+                fgetc(f);
+            }
+
+            if (lfs_cfg_match(f, ":")) {
+                fgetc(f);
+                while (lfs_cfg_match(f, " \t\v\f")) {
+                    fgetc(f);
+                }
+
+                unsigned val = cfg->blen;
+                while (!lfs_cfg_match(f, " \t\v\f#\r\n") && !feof(f)) {
+                    if ((err = lfs_cfg_buffer(cfg, fgetc(f)))) {
+                        return err;
+                    }
+                }
+                if ((err = lfs_cfg_buffer(cfg, 0))) {
+                    return err;
+                }
+
+                if ((err = lfs_cfg_attr(cfg, key, val))) {
+                    return err;
+                }
+            } else {
+                cfg->blen = key;
+            }
+        }
+
+        while (!lfs_cfg_match(f, "\r\n") && !feof(f)) {
+            fgetc(f);
+        }
+        fgetc(f);
+    }
+
+    return 0;
+}
+
+void lfs_cfg_destroy(lfs_cfg_t *cfg) {
+    free(cfg->attrs);
+}
+
+bool lfs_cfg_has(lfs_cfg_t *cfg, const char *key) {
+    return lfs_cfg_get(cfg, key, 0);
+}
+
+const char *lfs_cfg_get(lfs_cfg_t *cfg, const char *key, const char *def) {
+    // binary search for attribute
+    int lo = 0;
+    int hi = cfg->len-1;
+
+    while (lo <= hi) {
+        int i = (hi + lo) / 2;
+        int cmp = strcmp(key, &cfg->buf[cfg->attrs[i].key]);
+        if (cmp == 0) {
+            return &cfg->buf[cfg->attrs[i].val];
+        } else if (cmp < 0) {
+            hi = i-1;
+        } else {
+            lo = i+1;
+        }
+    }
+
+    return def;
+}
+
+ssize_t lfs_cfg_geti(lfs_cfg_t *cfg, const char *key, ssize_t def) {
+    const char *val = lfs_cfg_get(cfg, key, 0);
+    if (!val) {
+        return def;
+    }
+
+    char *end;
+    ssize_t res = strtoll(val, &end, 0);
+    return (end == val) ? def : res;
+}
+
+size_t lfs_cfg_getu(lfs_cfg_t *cfg, const char *key, size_t def) {
+    const char *val = lfs_cfg_get(cfg, key, 0);
+    if (!val) {
+        return def;
+    }
+
+    char *end;
+    size_t res = strtoull(val, &end, 0);
+    return (end == val) ? def : res;
+}
@@ -0,0 +1,74 @@
+/*
+ * Simple config parser
+ *
+ * Copyright (c) 2017 Christopher Haster
+ * Distributed under the MIT license
+ */
+#ifndef LFS_CFG_H
+#define LFS_CFG_H
+
+#include <stddef.h>
+#include <stdbool.h>
+#include <unistd.h>
+
+// This is a simple parser for config files
+//
+// The cfg file format is dumb simple. Attributes are
+// key value pairs separated by a single colon. Delimited
+// by comments (#) and newlines (\r\n) and trims
+// whitespace ( \t\v\f)
+//
+// Here's an example file
+// # Here is a dump example
+// looky: it's_an_attribute
+// hey_look: another_attribute
+//
+// huh: yeah_that's_basically_it # basically it
+
+// Internal config structure
+typedef struct lfs_cfg {
+    size_t len;
+    size_t size;
+
+    size_t blen;
+    size_t bsize;
+    char *buf;
+
+    struct lfs_cfg_attr {
+        unsigned key;
+        unsigned val;
+    } *attrs;
+} lfs_cfg_t;
+
+
+
+// Creates a cfg object and reads in the cfg file from the filename
+//
+// If the lfs_cfg_read fails, returns a negative value from the underlying
+// stdio functions
+int lfs_cfg_create(lfs_cfg_t *cfg, const char *filename);
+
+// Destroys the cfg object and frees any used memory
+void lfs_cfg_destroy(lfs_cfg_t *cfg);
+
+// Checks if a cfg attribute exists
+bool lfs_cfg_has(lfs_cfg_t *cfg, const char *key);
+
+// Retrieves a cfg attribute as a null-terminated string
+//
+// If the attribute does not exist, returns the string passed as def
+const char *lfs_cfg_get(lfs_cfg_t *cfg, const char *key, const char *def);
+
+// Retrieves a cfg attribute parsed as an int
+//
+// If the attribute does not exist or can't be parsed, returns the
+// integer passed as def
+ssize_t lfs_cfg_geti(lfs_cfg_t *cfg, const char *name, ssize_t def);
+
+// Retrieves a cfg attribute parsed as an unsigned int
+//
+// If the attribute does not exist or can't be parsed, returns the
+// integer passed as def
+size_t lfs_cfg_getu(lfs_cfg_t *cfg, const char *name, size_t def);
+
+#endif
@@ -0,0 +1,223 @@
+/*
+ * Block device emulated on standard files
+ *
+ * Copyright (c) 2017 Christopher Haster
+ * Distributed under the MIT license
+ */
+#include "emubd/lfs_emubd.h"
+#include "emubd/lfs_cfg.h"
+
+#include <errno.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <limits.h>
+#include <dirent.h>
+
+
+// Block device emulated on existing filesystem
+lfs_error_t lfs_emubd_create(lfs_emubd_t *emu, const char *path) {
+    memset(&emu->info, 0, sizeof(emu->info));
+
+    // Allocate buffer for creating children files
+    size_t pathlen = strlen(path);
+    emu->path = malloc(pathlen + 1 + LFS_NAME_MAX + 1);
+    if (!emu->path) {
+        return -ENOMEM;
+    }
+
+    strcpy(emu->path, path);
+    emu->path[pathlen] = '/';
+    emu->path[pathlen + 1 + LFS_NAME_MAX] = '\0';
+    emu->child = &emu->path[pathlen+1];
+    strncpy(emu->child, "config", LFS_NAME_MAX);
+
+    // Load config, erroring if it doesn't exist
+    lfs_cfg_t cfg;
+    int err = lfs_cfg_create(&cfg, emu->path);
+    if (err) {
+        return err;
+    }
+
+    emu->info.read_size = lfs_cfg_getu(&cfg,  "read_size",  0);
+    emu->info.write_size = lfs_cfg_getu(&cfg, "write_size", 0);
+    emu->info.erase_size = lfs_cfg_getu(&cfg, "erase_size", 0);
+    emu->info.total_size = lfs_cfg_getu(&cfg, "total_size", 0);
+
+    lfs_cfg_destroy(&cfg);
+
+    return 0;
+}
+
+void lfs_emubd_destroy(lfs_emubd_t *emu) {
+    free(emu->path);
+}
+
+lfs_error_t lfs_emubd_read(lfs_emubd_t *emu, uint8_t *buffer,
+        lfs_ino_t ino, lfs_off_t off, lfs_size_t size) {
+
+    // Check if read is valid
+    if (!(off % emu->info.read_size == 0 &&
+         size % emu->info.read_size == 0 &&
+         ((lfs_lsize_t)ino*emu->info.erase_size + off + size
+          < emu->info.total_size))) {
+        return -EINVAL;
+    }
+
+    // Default to some arbitrary value for debugging
+    memset(buffer, 0xcc, size);
+
+    // Iterate over blocks until enough data is read
+    while (size > 0) {
+        snprintf(emu->child, LFS_NAME_MAX, "%d", ino);
+        size_t count = lfs_min(emu->info.erase_size - off, size);
+
+        FILE *f = fopen(emu->path, "rb");
+        if (!f && errno != ENOENT) {
+            return -errno;
+        }
+
+        if (f) {
+            int err = fseek(f, off, SEEK_SET);
+            if (err) {
+                return -errno;
+            }
+
+            size_t res = fread(buffer, 1, count, f);
+            if (res < count && !feof(f)) {
+                return -errno;
+            }
+
+            err = fclose(f);
+            if (err) {
+                return -errno;
+            }
+        }
+
+        size -= count;
+        buffer += count;
+        ino += 1;
+        off = 0;
+    }
+
+    return 0;
+}
+
+lfs_error_t lfs_emubd_write(lfs_emubd_t *emu, const uint8_t *buffer,
+        lfs_ino_t ino, lfs_off_t off, lfs_size_t size) {
+
+    // Check if write is valid
+    if (!(off % emu->info.write_size == 0 &&
+         size % emu->info.write_size == 0 &&
+         ((lfs_lsize_t)ino*emu->info.erase_size + off + size
+          < emu->info.total_size))) {
+        return -EINVAL;
+    }
+
+    // Iterate over blocks until enough data is read
+    while (size > 0) {
+        snprintf(emu->child, LFS_NAME_MAX, "%d", ino);
+        size_t count = lfs_min(emu->info.erase_size - off, size);
+
+        FILE *f = fopen(emu->path, "r+b");
+        if (!f && errno == ENOENT) {
+            f = fopen(emu->path, "w+b");
+            if (!f) {
+                return -errno;
+            }
+        }
+
+        int err = fseek(f, off, SEEK_SET);
+        if (err) {
+            return -errno;
+        }
+
+        size_t res = fwrite(buffer, 1, count, f);
+        if (res < count) {
+            return -errno;
+        }
+
+        err = fclose(f);
+        if (err) {
+            return -errno;
+        }
+
+        size -= count;
+        buffer += count;
+        ino += 1;
+        off = 0;
+    }
+
+    return 0;
+}
+
+lfs_error_t lfs_emubd_erase(lfs_emubd_t *emu,
+        lfs_ino_t ino, lfs_off_t off, lfs_size_t size) {
+
+    // Check if erase is valid
+    if (!(off % emu->info.erase_size == 0 &&
+         size % emu->info.erase_size == 0 &&
+         ((lfs_lsize_t)ino*emu->info.erase_size + off + size
+          < emu->info.total_size))) {
+        return -EINVAL;
+    }
+
+    // Iterate and erase blocks
+    while (size > 0) {
+        snprintf(emu->child, LFS_NAME_MAX, "%d", ino);
+        int err = unlink(emu->path);
+        if (err && errno != ENOENT) {
+            return -errno;
+        }
+
+        size -= emu->info.erase_size;
+        ino += 1;
+        off = 0;
+    }
+
+    return 0;
+}
+
+lfs_error_t lfs_emubd_sync(lfs_emubd_t *emu) {
+    // Always in sync
+    return 0;
+}
+
+lfs_error_t lfs_emubd_info(lfs_emubd_t *emu, struct lfs_bd_info *info) {
+    *info = emu->info;
+    return 0;
+}
+
+
+// Wrappers for void*s
+static lfs_error_t lfs_emubd_bd_read(void *bd, uint8_t *buffer,
+        lfs_ino_t ino, lfs_off_t off, lfs_size_t size) {
+    return lfs_emubd_read((lfs_emubd_t*)bd, buffer, ino, off, size);
+}
+
+static lfs_error_t lfs_emubd_bd_write(void *bd, const uint8_t *buffer,
+        lfs_ino_t ino, lfs_off_t off, lfs_size_t size) {
+    return lfs_emubd_write((lfs_emubd_t*)bd, buffer, ino, off, size);
+}
+
+static lfs_error_t lfs_emubd_bd_erase(void *bd,
+        lfs_ino_t ino, lfs_off_t off, lfs_size_t size) {
+    return lfs_emubd_erase((lfs_emubd_t*)bd, ino, off, size);
+}
+
+static lfs_error_t lfs_emubd_bd_sync(void *bd) {
+    return lfs_emubd_sync((lfs_emubd_t*)bd);
+}
+
+static lfs_error_t lfs_emubd_bd_info(void *bd, struct lfs_bd_info *info) {
+    return lfs_emubd_info((lfs_emubd_t*)bd, info);
+}
+
+const struct lfs_bd_ops lfs_emubd_ops = {
+    .read = lfs_emubd_bd_read,
+    .write = lfs_emubd_bd_write,
+    .erase = lfs_emubd_bd_erase,
+    .sync = lfs_emubd_bd_sync,
+    .info = lfs_emubd_bd_info,
+};
+
@@ -0,0 +1,57 @@
+/*
+ * Block device emulated on standard files
+ *
+ * Copyright (c) 2017 Christopher Haster
+ * Distributed under the MIT license
+ */
+#ifndef LFS_EMUBD_H
+#define LFS_EMUBD_H
+
+#include "lfs_config.h"
+#include "lfs_bd.h"
+
+
+// The emu bd state
+typedef struct lfs_emubd {
+    char *path;
+    char *child;
+    struct lfs_bd_info info;
+} lfs_emubd_t;
+
+
+// Create a block device using path for the directory to store blocks
+lfs_error_t lfs_emubd_create(lfs_emubd_t *emu, const char *path);
+
+// Clean up memory associated with emu block device
+void lfs_emubd_destroy(lfs_emubd_t *emu);
+
+// Read a block
+lfs_error_t lfs_emubd_read(lfs_emubd_t *bd, uint8_t *buffer,
+        lfs_ino_t ino, lfs_off_t off, lfs_size_t size);
+
+// Program a block
+//
+// The block must have previously been erased.
+lfs_error_t lfs_emubd_write(lfs_emubd_t *bd, const uint8_t *buffer,
+        lfs_ino_t ino, lfs_off_t off, lfs_size_t size);
+
+// Erase a block
+//
+// A block must be erased before being programmed. The
+// state of an erased block is undefined.
+lfs_error_t lfs_emubd_erase(lfs_emubd_t *bd,
+        lfs_ino_t ino, lfs_off_t off, lfs_size_t size);
+
+// Sync the block device
+lfs_error_t lfs_emubd_sync(lfs_emubd_t *bd);
+
+// Get a description of the block device
+//
+// Any unknown information may be left unmodified
+lfs_error_t lfs_emubd_info(lfs_emubd_t *bd, struct lfs_bd_info *info);
+
+// Block device operations
+extern const struct lfs_bd_ops lfs_emubd_ops;
+
+
+#endif