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Removed recursion in file read/writes

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This mostly just required separate functions for "lfs_file_rawwrite" and
"lfs_file_flushedwrite", since lfs_file_flush recursively invokes
lfs_file_rawread and lfs_file_rawwrite.

This comes at a code cost, but gives us bounded and measurable RAM usage
on this code path.
This commit is contained in:
Christopher Haster
2022-02-27 23:05:25 -06:00
parent 84da4c0b1a
commit fedf646c79
1 changed files with 64 additions and 45 deletions
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107
lfs.c
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@@ -469,7 +469,8 @@ static int lfs_dir_commit(lfs_t *lfs, lfs_mdir_t *dir,
static int lfs_dir_compact(lfs_t *lfs,
lfs_mdir_t *dir, const struct lfs_mattr *attrs, int attrcount,
lfs_mdir_t *source, uint16_t begin, uint16_t end);
static lfs_ssize_t lfs_file_flushedwrite(lfs_t *lfs, lfs_file_t *file,
const void *buffer, lfs_size_t size);
static lfs_ssize_t lfs_file_rawwrite(lfs_t *lfs, lfs_file_t *file,
const void *buffer, lfs_size_t size);
static int lfs_file_rawsync(lfs_t *lfs, lfs_file_t *file);
@@ -494,6 +495,8 @@ static int lfs1_traverse(lfs_t *lfs,
static int lfs_dir_rawrewind(lfs_t *lfs, lfs_dir_t *dir);
static lfs_ssize_t lfs_file_flushedread(lfs_t *lfs, lfs_file_t *file,
void *buffer, lfs_size_t size);
static lfs_ssize_t lfs_file_rawread(lfs_t *lfs, lfs_file_t *file,
void *buffer, lfs_size_t size);
static int lfs_file_rawclose(lfs_t *lfs, lfs_file_t *file);
@@ -2983,12 +2986,12 @@ static int lfs_file_flush(lfs_t *lfs, lfs_file_t *file) {
// copy over a byte at a time, leave it up to caching
// to make this efficient
uint8_t data;
lfs_ssize_t res = lfs_file_rawread(lfs, &orig, &data, 1);
lfs_ssize_t res = lfs_file_flushedread(lfs, &orig, &data, 1);
if (res < 0) {
return res;
}
res = lfs_file_rawwrite(lfs, file, &data, 1);
res = lfs_file_flushedwrite(lfs, file, &data, 1);
if (res < 0) {
return res;
}
@@ -3089,23 +3092,11 @@ static int lfs_file_rawsync(lfs_t *lfs, lfs_file_t *file) {
}
#endif
static lfs_ssize_t lfs_file_rawread(lfs_t *lfs, lfs_file_t *file,
static lfs_ssize_t lfs_file_flushedread(lfs_t *lfs, lfs_file_t *file,
void *buffer, lfs_size_t size) {
LFS_ASSERT((file->flags & LFS_O_RDONLY) == LFS_O_RDONLY);
uint8_t *data = buffer;
lfs_size_t nsize = size;
#ifndef LFS_READONLY
if (file->flags & LFS_F_WRITING) {
// flush out any writes
int err = lfs_file_flush(lfs, file);
if (err) {
return err;
}
}
#endif
if (file->pos >= file->ctz.size) {
// eof if past end
return 0;
@@ -3162,43 +3153,29 @@ static lfs_ssize_t lfs_file_rawread(lfs_t *lfs, lfs_file_t *file,
return size;
}
static lfs_ssize_t lfs_file_rawread(lfs_t *lfs, lfs_file_t *file,
void *buffer, lfs_size_t size) {
LFS_ASSERT((file->flags & LFS_O_RDONLY) == LFS_O_RDONLY);
#ifndef LFS_READONLY
static lfs_ssize_t lfs_file_rawwrite(lfs_t *lfs, lfs_file_t *file,
const void *buffer, lfs_size_t size) {
LFS_ASSERT((file->flags & LFS_O_WRONLY) == LFS_O_WRONLY);
const uint8_t *data = buffer;
lfs_size_t nsize = size;
if (file->flags & LFS_F_READING) {
// drop any reads
if (file->flags & LFS_F_WRITING) {
// flush out any writes
int err = lfs_file_flush(lfs, file);
if (err) {
return err;
}
}
#endif
if ((file->flags & LFS_O_APPEND) && file->pos < file->ctz.size) {
file->pos = file->ctz.size;
return lfs_file_flushedread(lfs, file, buffer, size);
}
if (file->pos + size > lfs->file_max) {
// Larger than file limit?
return LFS_ERR_FBIG;
}
if (!(file->flags & LFS_F_WRITING) && file->pos > file->ctz.size) {
// fill with zeros
lfs_off_t pos = file->pos;
file->pos = file->ctz.size;
while (file->pos < pos) {
lfs_ssize_t res = lfs_file_rawwrite(lfs, file, &(uint8_t){0}, 1);
if (res < 0) {
return res;
}
}
}
#ifndef LFS_READONLY
static lfs_ssize_t lfs_file_flushedwrite(lfs_t *lfs, lfs_file_t *file,
const void *buffer, lfs_size_t size) {
const uint8_t *data = buffer;
lfs_size_t nsize = size;
if ((file->flags & LFS_F_INLINE) &&
lfs_max(file->pos+nsize, file->ctz.size) >
@@ -3280,9 +3257,51 @@ relocate:
lfs_alloc_ack(lfs);
}
file->flags &= ~LFS_F_ERRED;
return size;
}
static lfs_ssize_t lfs_file_rawwrite(lfs_t *lfs, lfs_file_t *file,
const void *buffer, lfs_size_t size) {
LFS_ASSERT((file->flags & LFS_O_WRONLY) == LFS_O_WRONLY);
if (file->flags & LFS_F_READING) {
// drop any reads
int err = lfs_file_flush(lfs, file);
if (err) {
return err;
}
}
if ((file->flags & LFS_O_APPEND) && file->pos < file->ctz.size) {
file->pos = file->ctz.size;
}
if (file->pos + size > lfs->file_max) {
// Larger than file limit?
return LFS_ERR_FBIG;
}
if (!(file->flags & LFS_F_WRITING) && file->pos > file->ctz.size) {
// fill with zeros
lfs_off_t pos = file->pos;
file->pos = file->ctz.size;
while (file->pos < pos) {
lfs_ssize_t res = lfs_file_flushedwrite(lfs, file, &(uint8_t){0}, 1);
if (res < 0) {
return res;
}
}
}
lfs_ssize_t nsize = lfs_file_flushedwrite(lfs, file, buffer, size);
if (nsize < 0) {
return nsize;
}
file->flags &= ~LFS_F_ERRED;
return nsize;
}
#endif
static lfs_soff_t lfs_file_rawseek(lfs_t *lfs, lfs_file_t *file,