Added proper handling for removing open files

Conveniently we previously added a linked-list of files
for things like this. This should handle most of the corner
cases where files are open during strange operations.

This also brings up the point that we aren't doing anything similar
for directories and don't even have a dir linked-list. After thinking
about it for a while, I've decided to leave out this handling for dirs.
It will likely be very complicated, with little gains as directories
are less used in embedded systems. Additionally, dirs are only open
for reading, and corruption will probably just cause the dir iteration
to terminate. If needed, correct handling of open directories can be
added later.

Makefile

@@ -31,7 +31,8 @@ size: $(OBJ)
 	$(SIZE) -t $^
 
 .SUFFIXES:
-test: test_format test_dirs test_files test_seek test_alloc test_paths test_orphan
+test: test_format test_dirs test_files test_seek test_parallel \
+	test_alloc test_paths test_orphan
 test_%: tests/test_%.sh
 	./$<
 

lfs.c

@@ -1155,7 +1155,7 @@ int lfs_file_sync(lfs_t *lfs, lfs_file_t *file) {
         return err;
     }
 
-    if (file->flags & LFS_F_DIRTY) {
+    if ((file->flags & LFS_F_DIRTY) && !lfs_pairisnull(file->pair)) {
         // update dir entry
         lfs_dir_t cwd;
         int err = lfs_dir_fetch(lfs, &cwd, file->pair);
@@ -1406,6 +1406,18 @@ int lfs_remove(lfs_t *lfs, const char *path) {
         return err;
     }
 
+    // shift over any files that are affected
+    for (lfs_file_t *f = lfs->files; f; f = f->next) {
+        if (lfs_paircmp(f->pair, cwd.pair) == 0) {
+            if (f->poff == entry.off) {
+                f->pair[0] = 0xffffffff;
+                f->pair[1] = 0xffffffff;
+            } else if (f->poff > entry.off) {
+                f->poff -= entry.d.len;
+            }
+        }
+    }
+
     // if we were a directory, just run a deorphan step, this should
     // collect us, although is expensive
     if (entry.d.type == LFS_TYPE_DIR) {
@@ -1498,6 +1510,18 @@ int lfs_rename(lfs_t *lfs, const char *oldpath, const char *newpath) {
         return err;
     }
 
+    // shift over any files that are affected
+    for (lfs_file_t *f = lfs->files; f; f = f->next) {
+        if (lfs_paircmp(f->pair, oldcwd.pair) == 0) {
+            if (f->poff == oldentry.off) {
+                f->pair[0] = 0xffffffff;
+                f->pair[1] = 0xffffffff;
+            } else if (f->poff > oldentry.off) {
+                f->poff -= oldentry.d.len;
+            }
+        }
+    }
+
     // if we were a directory, just run a deorphan step, this should
     // collect us, although is expensive
     if (prevexists && preventry.d.type == LFS_TYPE_DIR) {

tests/test_parallel.sh

@@ -0,0 +1,186 @@
+#!/bin/bash
+set -eu
+
+echo "=== Parallel tests ==="
+rm -rf blocks
+tests/test.py << TEST
+    lfs_format(&lfs, &cfg) => 0;
+TEST
+
+echo "--- Parallel file test ---"
+tests/test.py << TEST
+    lfs_mount(&lfs, &cfg) => 0;
+    lfs_file_open(&lfs, &file[0], "a", LFS_O_WRONLY | LFS_O_CREAT) => 0;
+    lfs_file_open(&lfs, &file[1], "b", LFS_O_WRONLY | LFS_O_CREAT) => 0;
+    lfs_file_open(&lfs, &file[2], "c", LFS_O_WRONLY | LFS_O_CREAT) => 0;
+    lfs_file_open(&lfs, &file[3], "d", LFS_O_WRONLY | LFS_O_CREAT) => 0;
+
+    for (int i = 0; i < 10; i++) {
+        lfs_file_write(&lfs, &file[0], (const void*)"a", 1) => 1;
+        lfs_file_write(&lfs, &file[1], (const void*)"b", 1) => 1;
+        lfs_file_write(&lfs, &file[2], (const void*)"c", 1) => 1;
+        lfs_file_write(&lfs, &file[3], (const void*)"d", 1) => 1;
+    }
+
+    lfs_file_close(&lfs, &file[0]);
+    lfs_file_close(&lfs, &file[1]);
+    lfs_file_close(&lfs, &file[2]);
+    lfs_file_close(&lfs, &file[3]);
+
+    lfs_dir_open(&lfs, &dir[0], "/") => 0;
+    lfs_dir_read(&lfs, &dir[0], &info) => 1;
+    strcmp(info.name, ".") => 0;
+    info.type => LFS_TYPE_DIR;
+    lfs_dir_read(&lfs, &dir[0], &info) => 1;
+    strcmp(info.name, "..") => 0;
+    info.type => LFS_TYPE_DIR;
+    lfs_dir_read(&lfs, &dir[0], &info) => 1;
+    strcmp(info.name, "a") => 0;
+    info.type => LFS_TYPE_REG;
+    info.size => 10;
+    lfs_dir_read(&lfs, &dir[0], &info) => 1;
+    strcmp(info.name, "b") => 0;
+    info.type => LFS_TYPE_REG;
+    info.size => 10;
+    lfs_dir_read(&lfs, &dir[0], &info) => 1;
+    strcmp(info.name, "c") => 0;
+    info.type => LFS_TYPE_REG;
+    info.size => 10;
+    lfs_dir_read(&lfs, &dir[0], &info) => 1;
+    strcmp(info.name, "d") => 0;
+    info.type => LFS_TYPE_REG;
+    info.size => 10;
+    lfs_dir_read(&lfs, &dir[0], &info) => 0;
+    lfs_dir_close(&lfs, &dir[0]) => 0;
+
+    lfs_file_open(&lfs, &file[0], "a", LFS_O_RDONLY) => 0;
+    lfs_file_open(&lfs, &file[1], "b", LFS_O_RDONLY) => 0;
+    lfs_file_open(&lfs, &file[2], "c", LFS_O_RDONLY) => 0;
+    lfs_file_open(&lfs, &file[3], "d", LFS_O_RDONLY) => 0;
+
+    for (int i = 0; i < 10; i++) {
+        lfs_file_read(&lfs, &file[0], buffer, 1) => 1;
+        buffer[0] => 'a';
+        lfs_file_read(&lfs, &file[1], buffer, 1) => 1;
+        buffer[0] => 'b';
+        lfs_file_read(&lfs, &file[2], buffer, 1) => 1;
+        buffer[0] => 'c';
+        lfs_file_read(&lfs, &file[3], buffer, 1) => 1;
+        buffer[0] => 'd';
+    }
+
+    lfs_file_close(&lfs, &file[0]);
+    lfs_file_close(&lfs, &file[1]);
+    lfs_file_close(&lfs, &file[2]);
+    lfs_file_close(&lfs, &file[3]);
+    
+    lfs_unmount(&lfs) => 0;
+TEST
+
+echo "--- Parallel remove file test ---"
+tests/test.py << TEST
+    lfs_mount(&lfs, &cfg) => 0;
+    lfs_file_open(&lfs, &file[0], "e", LFS_O_WRONLY | LFS_O_CREAT) => 0;
+
+    for (int i = 0; i < 5; i++) {
+        lfs_file_write(&lfs, &file[0], (const void*)"e", 1) => 1;
+    }
+
+    lfs_remove(&lfs, "a") => 0;
+    lfs_remove(&lfs, "b") => 0;
+    lfs_remove(&lfs, "c") => 0;
+    lfs_remove(&lfs, "d") => 0;
+
+    for (int i = 0; i < 5; i++) {
+        lfs_file_write(&lfs, &file[0], (const void*)"e", 1) => 1;
+    }
+
+    lfs_file_close(&lfs, &file[0]);
+
+    lfs_dir_open(&lfs, &dir[0], "/") => 0;
+    lfs_dir_read(&lfs, &dir[0], &info) => 1;
+    strcmp(info.name, ".") => 0;
+    info.type => LFS_TYPE_DIR;
+    lfs_dir_read(&lfs, &dir[0], &info) => 1;
+    strcmp(info.name, "..") => 0;
+    info.type => LFS_TYPE_DIR;
+    lfs_dir_read(&lfs, &dir[0], &info) => 1;
+    strcmp(info.name, "e") => 0;
+    info.type => LFS_TYPE_REG;
+    info.size => 10;
+    lfs_dir_read(&lfs, &dir[0], &info) => 0;
+    lfs_dir_close(&lfs, &dir[0]) => 0;
+
+    lfs_file_open(&lfs, &file[0], "e", LFS_O_RDONLY) => 0;
+
+    for (int i = 0; i < 10; i++) {
+        lfs_file_read(&lfs, &file[0], buffer, 1) => 1;
+        buffer[0] => 'e';
+    }
+
+    lfs_file_close(&lfs, &file[0]);
+    
+    lfs_unmount(&lfs) => 0;
+TEST
+
+echo "--- Remove inconveniently test ---"
+tests/test.py << TEST
+    lfs_mount(&lfs, &cfg) => 0;
+    lfs_file_open(&lfs, &file[0], "e", LFS_O_WRONLY | LFS_O_TRUNC) => 0;
+    lfs_file_open(&lfs, &file[1], "f", LFS_O_WRONLY | LFS_O_CREAT) => 0;
+    lfs_file_open(&lfs, &file[2], "g", LFS_O_WRONLY | LFS_O_CREAT) => 0;
+
+    for (int i = 0; i < 5; i++) {
+        lfs_file_write(&lfs, &file[0], (const void*)"e", 1) => 1;
+        lfs_file_write(&lfs, &file[1], (const void*)"f", 1) => 1;
+        lfs_file_write(&lfs, &file[2], (const void*)"g", 1) => 1;
+    }
+
+    lfs_remove(&lfs, "f") => 0;
+
+    for (int i = 0; i < 5; i++) {
+        lfs_file_write(&lfs, &file[0], (const void*)"e", 1) => 1;
+        lfs_file_write(&lfs, &file[1], (const void*)"f", 1) => 1;
+        lfs_file_write(&lfs, &file[2], (const void*)"g", 1) => 1;
+    }
+
+    lfs_file_close(&lfs, &file[0]);
+    lfs_file_close(&lfs, &file[1]);
+    lfs_file_close(&lfs, &file[2]);
+
+    lfs_dir_open(&lfs, &dir[0], "/") => 0;
+    lfs_dir_read(&lfs, &dir[0], &info) => 1;
+    strcmp(info.name, ".") => 0;
+    info.type => LFS_TYPE_DIR;
+    lfs_dir_read(&lfs, &dir[0], &info) => 1;
+    strcmp(info.name, "..") => 0;
+    info.type => LFS_TYPE_DIR;
+    lfs_dir_read(&lfs, &dir[0], &info) => 1;
+    strcmp(info.name, "e") => 0;
+    info.type => LFS_TYPE_REG;
+    info.size => 10;
+    lfs_dir_read(&lfs, &dir[0], &info) => 1;
+    strcmp(info.name, "g") => 0;
+    info.type => LFS_TYPE_REG;
+    info.size => 10;
+    lfs_dir_read(&lfs, &dir[0], &info) => 0;
+    lfs_dir_close(&lfs, &dir[0]) => 0;
+
+    lfs_file_open(&lfs, &file[0], "e", LFS_O_RDONLY) => 0;
+    lfs_file_open(&lfs, &file[1], "g", LFS_O_RDONLY) => 0;
+
+    for (int i = 0; i < 10; i++) {
+        lfs_file_read(&lfs, &file[0], buffer, 1) => 1;
+        buffer[0] => 'e';
+        lfs_file_read(&lfs, &file[1], buffer, 1) => 1;
+        buffer[0] => 'g';
+    }
+
+    lfs_file_close(&lfs, &file[0]);
+    lfs_file_close(&lfs, &file[1]);
+    
+    lfs_unmount(&lfs) => 0;
+TEST
+
+echo "--- Results ---"
+tests/stats.py