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Moved emulation of erase values up into lfs_testbd
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Yes this is more expensive, since small programs need to rewrite the
whole block in order to conform to the block device API. However, it
reduces code duplication and keeps all of the test-related block device
emulation in lfs_testbd.

Some people have used lfs_filebd/lfs_rambd as a starting point for new block
devices and I think it should be clear that erase does not need to have side
effects. Though to be fair this also just means we should have more
examples of block devices...
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@geky
geky committed Aug 17, 2022
1 parent b08463f commit a368d3a
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Showing 6 changed files with 114 additions and 134 deletions.
85 changes: 13 additions & 72 deletions bd/lfs_filebd.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -15,21 +15,18 @@
#include <windows.h>
#endif

int lfs_filebd_createcfg(const struct lfs_config *cfg, const char *path,
const struct lfs_filebd_config *bdcfg) {
LFS_FILEBD_TRACE("lfs_filebd_createcfg(%p {.context=%p, "
int lfs_filebd_create(const struct lfs_config *cfg, const char *path) {
LFS_FILEBD_TRACE("lfs_filebd_create(%p {.context=%p, "
".read=%p, .prog=%p, .erase=%p, .sync=%p, "
".read_size=%"PRIu32", .prog_size=%"PRIu32", "
".block_size=%"PRIu32", .block_count=%"PRIu32"}, "
"\"%s\", "
"%p {.erase_value=%"PRId32"})",
"\"%s\")",
(void*)cfg, cfg->context,
(void*)(uintptr_t)cfg->read, (void*)(uintptr_t)cfg->prog,
(void*)(uintptr_t)cfg->erase, (void*)(uintptr_t)cfg->sync,
cfg->read_size, cfg->prog_size, cfg->block_size, cfg->block_count,
path, (void*)bdcfg, bdcfg->erase_value);
lfs_filebd_t *bd = cfg->context;
bd->cfg = bdcfg;

// open file
#ifdef _WIN32
Expand All @@ -40,31 +37,14 @@ int lfs_filebd_createcfg(const struct lfs_config *cfg, const char *path,

if (bd->fd < 0) {
int err = -errno;
LFS_FILEBD_TRACE("lfs_filebd_createcfg -> %d", err);
LFS_FILEBD_TRACE("lfs_filebd_create -> %d", err);
return err;
}

LFS_FILEBD_TRACE("lfs_filebd_createcfg -> %d", 0);
LFS_FILEBD_TRACE("lfs_filebd_create -> %d", 0);
return 0;
}

int lfs_filebd_create(const struct lfs_config *cfg, const char *path) {
LFS_FILEBD_TRACE("lfs_filebd_create(%p {.context=%p, "
".read=%p, .prog=%p, .erase=%p, .sync=%p, "
".read_size=%"PRIu32", .prog_size=%"PRIu32", "
".block_size=%"PRIu32", .block_count=%"PRIu32"}, "
"\"%s\")",
(void*)cfg, cfg->context,
(void*)(uintptr_t)cfg->read, (void*)(uintptr_t)cfg->prog,
(void*)(uintptr_t)cfg->erase, (void*)(uintptr_t)cfg->sync,
cfg->read_size, cfg->prog_size, cfg->block_size, cfg->block_count,
path);
static const struct lfs_filebd_config defaults = {.erase_value=-1};
int err = lfs_filebd_createcfg(cfg, path, &defaults);
LFS_FILEBD_TRACE("lfs_filebd_create -> %d", err);
return err;
}

int lfs_filebd_destroy(const struct lfs_config *cfg) {
LFS_FILEBD_TRACE("lfs_filebd_destroy(%p)", (void*)cfg);
lfs_filebd_t *bd = cfg->context;
Expand All @@ -86,14 +66,13 @@ int lfs_filebd_read(const struct lfs_config *cfg, lfs_block_t block,
lfs_filebd_t *bd = cfg->context;

// check if read is valid
LFS_ASSERT(block < cfg->block_count);
LFS_ASSERT(off % cfg->read_size == 0);
LFS_ASSERT(size % cfg->read_size == 0);
LFS_ASSERT(block < cfg->block_count);
LFS_ASSERT(off+size <= cfg->block_size);

// zero for reproducibility (in case file is truncated)
if (bd->cfg->erase_value != -1) {
memset(buffer, bd->cfg->erase_value, size);
}
memset(buffer, 0, size);

// read
off_t res1 = lseek(bd->fd,
Expand Down Expand Up @@ -122,32 +101,10 @@ int lfs_filebd_prog(const struct lfs_config *cfg, lfs_block_t block,
lfs_filebd_t *bd = cfg->context;

// check if write is valid
LFS_ASSERT(block < cfg->block_count);
LFS_ASSERT(off % cfg->prog_size == 0);
LFS_ASSERT(size % cfg->prog_size == 0);
LFS_ASSERT(block < cfg->block_count);

// check that data was erased? only needed for testing
if (bd->cfg->erase_value != -1) {
off_t res1 = lseek(bd->fd,
(off_t)block*cfg->block_size + (off_t)off, SEEK_SET);
if (res1 < 0) {
int err = -errno;
LFS_FILEBD_TRACE("lfs_filebd_prog -> %d", err);
return err;
}

for (lfs_off_t i = 0; i < size; i++) {
uint8_t c;
ssize_t res2 = read(bd->fd, &c, 1);
if (res2 < 0) {
int err = -errno;
LFS_FILEBD_TRACE("lfs_filebd_prog -> %d", err);
return err;
}

LFS_ASSERT(c == bd->cfg->erase_value);
}
}
LFS_ASSERT(off+size <= cfg->block_size);

// program data
off_t res1 = lseek(bd->fd,
Expand All @@ -171,36 +128,20 @@ int lfs_filebd_prog(const struct lfs_config *cfg, lfs_block_t block,

int lfs_filebd_erase(const struct lfs_config *cfg, lfs_block_t block) {
LFS_FILEBD_TRACE("lfs_filebd_erase(%p, 0x%"PRIx32")", (void*)cfg, block);
lfs_filebd_t *bd = cfg->context;

// check if erase is valid
LFS_ASSERT(block < cfg->block_count);

// erase, only needed for testing
if (bd->cfg->erase_value != -1) {
off_t res1 = lseek(bd->fd, (off_t)block*cfg->block_size, SEEK_SET);
if (res1 < 0) {
int err = -errno;
LFS_FILEBD_TRACE("lfs_filebd_erase -> %d", err);
return err;
}

for (lfs_off_t i = 0; i < cfg->block_size; i++) {
ssize_t res2 = write(bd->fd, &(uint8_t){bd->cfg->erase_value}, 1);
if (res2 < 0) {
int err = -errno;
LFS_FILEBD_TRACE("lfs_filebd_erase -> %d", err);
return err;
}
}
}
// erase is a noop
(void)block;

LFS_FILEBD_TRACE("lfs_filebd_erase -> %d", 0);
return 0;
}

int lfs_filebd_sync(const struct lfs_config *cfg) {
LFS_FILEBD_TRACE("lfs_filebd_sync(%p)", (void*)cfg);

// file sync
lfs_filebd_t *bd = cfg->context;
#ifdef _WIN32
Expand Down
11 changes: 0 additions & 11 deletions bd/lfs_filebd.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -26,25 +26,14 @@ extern "C"
#endif
#endif

// filebd config (optional)
struct lfs_filebd_config {
// 8-bit erase value to use for simulating erases. -1 does not simulate
// erases, which can speed up testing by avoiding all the extra block-device
// operations to store the erase value.
int32_t erase_value;
};

// filebd state
typedef struct lfs_filebd {
int fd;
const struct lfs_filebd_config *cfg;
} lfs_filebd_t;


// Create a file block device using the geometry in lfs_config
int lfs_filebd_create(const struct lfs_config *cfg, const char *path);
int lfs_filebd_createcfg(const struct lfs_config *cfg, const char *path,
const struct lfs_filebd_config *bdcfg);

// Clean up memory associated with block device
int lfs_filebd_destroy(const struct lfs_config *cfg);
Expand Down
41 changes: 14 additions & 27 deletions bd/lfs_rambd.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -13,12 +13,12 @@ int lfs_rambd_createcfg(const struct lfs_config *cfg,
".read=%p, .prog=%p, .erase=%p, .sync=%p, "
".read_size=%"PRIu32", .prog_size=%"PRIu32", "
".block_size=%"PRIu32", .block_count=%"PRIu32"}, "
"%p {.erase_value=%"PRId32", .buffer=%p})",
"%p {.buffer=%p})",
(void*)cfg, cfg->context,
(void*)(uintptr_t)cfg->read, (void*)(uintptr_t)cfg->prog,
(void*)(uintptr_t)cfg->erase, (void*)(uintptr_t)cfg->sync,
cfg->read_size, cfg->prog_size, cfg->block_size, cfg->block_count,
(void*)bdcfg, bdcfg->erase_value, bdcfg->buffer);
(void*)bdcfg, bdcfg->buffer);
lfs_rambd_t *bd = cfg->context;
bd->cfg = bdcfg;

Expand All @@ -33,13 +33,8 @@ int lfs_rambd_createcfg(const struct lfs_config *cfg,
}
}

// zero for reproducibility?
if (bd->cfg->erase_value != -1) {
memset(bd->buffer, bd->cfg->erase_value,
cfg->block_size * cfg->block_count);
} else {
memset(bd->buffer, 0, cfg->block_size * cfg->block_count);
}
// zero for reproducibility
memset(bd->buffer, 0, cfg->block_size * cfg->block_count);

LFS_RAMBD_TRACE("lfs_rambd_createcfg -> %d", 0);
return 0;
Expand All @@ -54,7 +49,7 @@ int lfs_rambd_create(const struct lfs_config *cfg) {
(void*)(uintptr_t)cfg->read, (void*)(uintptr_t)cfg->prog,
(void*)(uintptr_t)cfg->erase, (void*)(uintptr_t)cfg->sync,
cfg->read_size, cfg->prog_size, cfg->block_size, cfg->block_count);
static const struct lfs_rambd_config defaults = {.erase_value=-1};
static const struct lfs_rambd_config defaults = {0};
int err = lfs_rambd_createcfg(cfg, &defaults);
LFS_RAMBD_TRACE("lfs_rambd_create -> %d", err);
return err;
Expand All @@ -79,9 +74,10 @@ int lfs_rambd_read(const struct lfs_config *cfg, lfs_block_t block,
lfs_rambd_t *bd = cfg->context;

// check if read is valid
LFS_ASSERT(block < cfg->block_count);
LFS_ASSERT(off % cfg->read_size == 0);
LFS_ASSERT(size % cfg->read_size == 0);
LFS_ASSERT(block < cfg->block_count);
LFS_ASSERT(off+size <= cfg->block_size);

// read data
memcpy(buffer, &bd->buffer[block*cfg->block_size + off], size);
Expand All @@ -98,17 +94,10 @@ int lfs_rambd_prog(const struct lfs_config *cfg, lfs_block_t block,
lfs_rambd_t *bd = cfg->context;

// check if write is valid
LFS_ASSERT(block < cfg->block_count);
LFS_ASSERT(off % cfg->prog_size == 0);
LFS_ASSERT(size % cfg->prog_size == 0);
LFS_ASSERT(block < cfg->block_count);

// check that data was erased? only needed for testing
if (bd->cfg->erase_value != -1) {
for (lfs_off_t i = 0; i < size; i++) {
LFS_ASSERT(bd->buffer[block*cfg->block_size + off + i] ==
bd->cfg->erase_value);
}
}
LFS_ASSERT(off+size <= cfg->block_size);

// program data
memcpy(&bd->buffer[block*cfg->block_size + off], buffer, size);
Expand All @@ -119,25 +108,23 @@ int lfs_rambd_prog(const struct lfs_config *cfg, lfs_block_t block,

int lfs_rambd_erase(const struct lfs_config *cfg, lfs_block_t block) {
LFS_RAMBD_TRACE("lfs_rambd_erase(%p, 0x%"PRIx32")", (void*)cfg, block);
lfs_rambd_t *bd = cfg->context;

// check if erase is valid
LFS_ASSERT(block < cfg->block_count);

// erase, only needed for testing
if (bd->cfg->erase_value != -1) {
memset(&bd->buffer[block*cfg->block_size],
bd->cfg->erase_value, cfg->block_size);
}
// erase is a noop
(void)block;

LFS_RAMBD_TRACE("lfs_rambd_erase -> %d", 0);
return 0;
}

int lfs_rambd_sync(const struct lfs_config *cfg) {
LFS_RAMBD_TRACE("lfs_rambd_sync(%p)", (void*)cfg);
// sync does nothing because we aren't backed by anything real

// sync is a noop
(void)cfg;

LFS_RAMBD_TRACE("lfs_rambd_sync -> %d", 0);
return 0;
}
4 changes: 0 additions & 4 deletions bd/lfs_rambd.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -28,10 +28,6 @@ extern "C"

// rambd config (optional)
struct lfs_rambd_config {
// 8-bit erase value to simulate erasing with. -1 indicates no erase
// occurs, which is still a valid block device
int32_t erase_value;

// Optional statically allocated buffer for the block device.
void *buffer;
};
Expand Down

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