commit 815cfbbceffc92363de61a15613290b1b2fb52a7
Author: thematdev <thematdev@thematdev.org>
Date:   Thu Jun 15 01:44:02 2023 +0300

    First commit

diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..68a49da
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,24 @@
+This is free and unencumbered software released into the public domain.
+
+Anyone is free to copy, modify, publish, use, compile, sell, or
+distribute this software, either in source code form or as a compiled
+binary, for any purpose, commercial or non-commercial, and by any
+means.
+
+In jurisdictions that recognize copyright laws, the author or authors
+of this software dedicate any and all copyright interest in the
+software to the public domain. We make this dedication for the benefit
+of the public at large and to the detriment of our heirs and
+successors. We intend this dedication to be an overt act of
+relinquishment in perpetuity of all present and future rights to this
+software under copyright law.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+OTHER DEALINGS IN THE SOFTWARE.
+
+For more information, please refer to <http://unlicense.org/>
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..cf63eee
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,23 @@
+TARGET_LIB ?= libqments.a
+
+BD ?= build
+SRC_DIRS ?= src
+INCLUDE_DIRS ?= include
+
+SRC_FILES := $(shell find $(SRC_DIRS) -name *.c)
+OBJ_FILES := $(patsubst %.c,$(BD)/%.o,$(SRC_FILES))
+
+$(BD)/$(TARGET_LIB): $(OBJ_FILES)
+	mkdir -p $(@D)
+	ar rcs $@ $(OBJ_FILES)
+
+$(BD)/%.o: %.c
+	mkdir -p $(@D)
+	$(CC) $(CFLAGS) -c $< -o $@ -I $(INCLUDE_DIRS)
+
+all: $(BD)/$(TARGET_LIB)
+
+clean:
+	rm -rfI $(BD)/
+
+.PHONY: all clean
diff --git a/examples/main.c b/examples/main.c
new file mode 100644
index 0000000..c1e5143
--- /dev/null
+++ b/examples/main.c
@@ -0,0 +1,66 @@
+/* Reads text from stdio and creates comment using unix fs driver in current directory */
+/* TODO: add path, displayname as arguments */
+
+#include <stdio.h>
+#include <time.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <pwd.h>
+#include <sys/types.h>
+
+#include "comment.h"
+#include "driver.h"
+#include "drivers/unix_fs/unix_fs_driver.h"
+
+char *
+get_username()
+{
+    uid_t uid = geteuid();
+    struct passwd *pw = getpwuid(uid);
+    if (pw) {
+        return pw->pw_name;
+    }
+    return "";
+}
+
+int
+main(int argc, const char *argv[])
+{
+    const Driver *driver = &unix_fs_driver;
+    char *path = ".";
+
+    char *user_sid = get_username();
+    char *user_displayname = user_sid;
+    int reply_id = 0;
+
+    size_t cur_buf_size = 256;
+    size_t idx = 0;
+
+    char *text = malloc(cur_buf_size);
+
+    int ch;
+    while ((ch = getchar()) != EOF) {
+        if (idx + 1 == cur_buf_size) {
+            cur_buf_size *= 2;
+            text = realloc(text, cur_buf_size);
+        }
+        text[idx++] = ch;
+    }
+    text[idx] = '\0';
+
+    time_t current_time;
+    time(&current_time);
+
+    UnixFsDriverData driver_data = { path };
+
+    CommentHeader *header = mk_comment_header(reply_id, current_time, strlen(text), user_sid, user_displayname);
+
+    int retval = driver->leave_comment(&driver_data, header, text);
+    free(text);
+    if (retval < 0) {
+        return retval;
+    } else {
+        return 0;
+    }
+}
diff --git a/include/comment.h b/include/comment.h
new file mode 100644
index 0000000..19426b3
--- /dev/null
+++ b/include/comment.h
@@ -0,0 +1,24 @@
+#ifndef COMMENT_H
+#define COMMENT_H
+
+#include <string.h>
+#include <time.h>
+
+typedef struct {
+    int reply_id; /* should be 0 if comment is top-level */
+    time_t creation_time;
+    size_t text_length;
+    char *user_sid, *user_displayname;
+} CommentHeader;
+
+typedef struct {
+    int id;
+    CommentHeader *header;
+    char *text;
+} Comment;
+
+/* does not copy strings given by pointers */
+CommentHeader *
+mk_comment_header(int reply_id, time_t creation_time, size_t text_length, char *user_sid, char *user_displayname);
+
+#endif /* COMMENT_H */
diff --git a/include/driver.h b/include/driver.h
new file mode 100644
index 0000000..7dfb268
--- /dev/null
+++ b/include/driver.h
@@ -0,0 +1,15 @@
+#ifndef DRIVER_H
+#define DRIVER_H
+
+#include "comment.h"
+
+typedef struct {
+    /* should return (id > 0) on success, and negative number on error */
+    int (*leave_comment)(void*, CommentHeader*, char*);
+    /* retrieve header information by id */
+    int (*get_header)(void*, CommentHeader*, int);
+    /* retrieve text of comment by id */
+    int (*get_text)(void*, char*, int);
+} Driver;
+
+#endif /* DRIVER_H */
diff --git a/include/drivers/unix_fs/unix_fs_driver.h b/include/drivers/unix_fs/unix_fs_driver.h
new file mode 100644
index 0000000..60ec7d3
--- /dev/null
+++ b/include/drivers/unix_fs/unix_fs_driver.h
@@ -0,0 +1,22 @@
+#ifndef UNIX_FS_DRIVER_H
+#define UNIX_FS_DRIVER_H
+
+#include "driver.h"
+
+#define ID_CTRL_FILE "max_id"
+#define TEXT_FILE_FMT "%s/%d.txt"
+#define HEADER_FILE_FMT "%s/%d.header"
+
+typedef struct {
+    char *path;
+} UnixFsDriverData;
+
+int unix_fs_driver_leave_comment(void *driver_data_ptr, CommentHeader *header, char *text);
+
+int unix_fs_driver_get_header(void *driver_data_ptr, CommentHeader *header, int id);
+
+int unix_fs_driver_get_text(void *driver_data_ptr, char *text, int id);
+
+static const Driver unix_fs_driver = { unix_fs_driver_leave_comment, unix_fs_driver_get_header, unix_fs_driver_get_text };
+
+#endif /* UNIX_FS_DRIVER_H */
diff --git a/src/comment.c b/src/comment.c
new file mode 100644
index 0000000..de3ecf1
--- /dev/null
+++ b/src/comment.c
@@ -0,0 +1,17 @@
+#include "comment.h"
+#include <stdlib.h>
+
+CommentHeader *
+mk_comment_header(int reply_id, time_t creation_time, size_t text_length, char *user_sid, char *user_displayname)
+{
+    CommentHeader *header = malloc(sizeof(CommentHeader));
+    
+    header->reply_id = reply_id;
+    header->creation_time = creation_time;
+    header->text_length = text_length;
+
+    header->user_sid = user_sid;
+    header->user_displayname = user_displayname;
+
+    return header;
+}
diff --git a/src/drivers/unix_fs/unix_fs_driver.c b/src/drivers/unix_fs/unix_fs_driver.c
new file mode 100644
index 0000000..387b2d7
--- /dev/null
+++ b/src/drivers/unix_fs/unix_fs_driver.c
@@ -0,0 +1,234 @@
+#define _GNU_SOURCE /* ahh, didn't know asprintf is a GNU extension */
+/* TODO: remove this bullshit */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+
+#include "comment.h"
+#include "drivers/unix_fs/unix_fs_driver.h"
+
+#define READ_BUF_SZ 256
+
+int
+is_valid_directory(const char *path)
+{
+    struct stat path_stat;
+    if (stat(path, &path_stat) != 0) {
+        return 0;
+    }
+    return S_ISDIR(path_stat.st_mode);
+}
+
+/* TODO: handle errors */
+int
+serialize_header(int fd, const CommentHeader *header)
+{
+    write(fd, &header->reply_id, sizeof(int));
+    write(fd, &header->creation_time, sizeof(time_t));
+    write(fd, &header->text_length, sizeof(size_t));
+    write(fd, header->user_sid, strlen(header->user_sid) + 1);
+    write(fd, header->user_displayname, strlen(header->user_displayname) + 1);
+    return 0;
+}
+
+/* TODO: handle errors */
+/* header string buffers must be long enough */
+int
+deserialize_header(int fd, CommentHeader *header)
+{
+    char buf[READ_BUF_SZ], *dst_bufs[2];
+    int bytes_read;
+    size_t len, dst_idx, i;
+
+    dst_bufs[0] = header->user_sid;
+    dst_bufs[1] = header->user_displayname;
+    dst_idx = 0;
+
+    read(fd, &header->reply_id, sizeof(int));
+    read(fd, &header->creation_time, sizeof(time_t));
+    read(fd, &header->text_length, sizeof(size_t));
+
+    while ((bytes_read = read(fd, buf, READ_BUF_SZ))) {
+        for (; i < bytes_read; ++i) {
+            if (buf[i] != '\0') {
+                *(dst_bufs[dst_idx]++) = buf[i];
+            } else {
+                dst_idx++;
+            }
+        }
+    }
+    return 0;
+}
+
+int
+unix_fs_driver_leave_comment(void *driver_data_ptr, CommentHeader *header, char *text)
+{
+    char *path, *header_file_path, *text_file_path, *id_ctrl_file_path;
+    FILE *id_ctrl_file;
+    size_t path_len, text_len;
+    int max_id;
+    int retval;
+    int header_fd, text_fd, id_ctrl_fd;
+    
+    /* assure safe free calls */
+    id_ctrl_file_path = header_file_path = text_file_path = NULL;
+    id_ctrl_file = NULL;
+
+    header_fd = text_fd = -1;
+
+    path = ((UnixFsDriverData*) driver_data_ptr)->path;
+    if (!is_valid_directory(path)) {
+        retval = -EINVAL;
+        goto defer;
+    }
+
+    path_len = strlen(path);
+    text_len = strlen(text);
+    
+    if (asprintf(&id_ctrl_file_path, "%s/%s", path, ID_CTRL_FILE) < 0) {
+        id_ctrl_file_path = NULL;
+        retval = -ENOMEM;
+        goto defer;
+    }
+
+    id_ctrl_file = fopen(id_ctrl_file_path, "r+");
+
+    if (!id_ctrl_file) {
+        retval = -EIO;
+        goto defer;
+    }
+
+    id_ctrl_fd = fileno(id_ctrl_file);
+    
+    if (lockf(id_ctrl_fd, F_LOCK, 0) < 0) {
+        id_ctrl_fd = -1;
+        retval = -EIO;
+        goto defer;
+    }
+    
+    if (fscanf(id_ctrl_file, "%d", &max_id) != 1) {
+        max_id = 1;
+    }
+
+    if (asprintf(&header_file_path, HEADER_FILE_FMT, path, max_id) < 0) {
+        header_file_path = NULL;
+        retval = -ENOMEM;
+        goto defer;
+    }
+    if (asprintf(&text_file_path, TEXT_FILE_FMT, path, max_id) < 0) {
+        text_file_path = NULL;
+        retval = -ENOMEM;
+        goto defer;
+    };
+
+    header_fd = open(header_file_path, O_RDWR | O_CREAT, 0644);
+    text_fd = open(text_file_path, O_RDWR | O_CREAT, 0644);
+
+    if (header_fd < 0 || text_fd < 0) {
+        retval = -EINVAL;
+        goto defer;
+    }
+   
+    if (write(text_fd, text, text_len) < text_len) {
+        retval = -EIO;
+        goto defer;
+    }
+    
+    retval = serialize_header(header_fd, header);
+    if (retval < 0) {
+        goto defer;
+    }
+    
+    if (!(id_ctrl_file = freopen(id_ctrl_file_path, "w+", id_ctrl_file))) {
+        retval = -EIO;
+        goto defer;
+    }
+    
+    fprintf(id_ctrl_file, "%d", max_id + 1); /* update id only on success */
+    retval = max_id + 1;
+defer:
+    if (id_ctrl_fd >= 0) {
+        if (lockf(id_ctrl_fd, F_ULOCK, 0) < 0) {
+            fprintf(stderr, "Failed to release id control lock, aborting...\n");
+            abort();
+        }
+    }
+    if (id_ctrl_file) fclose(id_ctrl_file);
+    free(id_ctrl_file_path);
+    free(header_file_path);
+    free(text_file_path);
+    if (header_fd >= 0) close(header_fd);
+    if (text_fd >= 0) close(text_fd);
+    return retval;
+}
+
+int
+unix_fs_driver_get_header(void *driver_data_ptr, CommentHeader *header, int id)
+{
+    char *path, *header_file_path;
+    int fd, retval;
+    
+    path = ((UnixFsDriverData*) driver_data_ptr)->path;
+    if (!asprintf(&header_file_path, HEADER_FILE_FMT, path, id)) {
+        return -ENOMEM;
+    }
+
+    fd = open(header_file_path, O_RDONLY);
+    if (fd < 0) {
+        free(header_file_path);
+        return -EIO;
+    }
+
+    retval = deserialize_header(fd, header);
+    free(header_file_path);
+    close(fd);
+    return retval;
+}
+
+int
+unix_fs_driver_get_text(void *driver_data_ptr, char *text, int id)
+{
+    char *path, *text_file_path;
+    int fd, retval;
+    off_t length;
+
+    path = ((UnixFsDriverData*) driver_data_ptr)->path;
+    if (!asprintf(&text_file_path, TEXT_FILE_FMT, path, id)) {
+        return -ENOMEM;
+    }
+
+    fd = open(text_file_path, O_RDONLY);
+    if (fd < 0) {
+        retval = -EIO;
+        goto defer;
+    }
+
+    length = lseek(fd, 0, SEEK_END);
+    if (length < 0) {
+        retval = -EIO;
+        goto defer;
+    }
+    if (lseek(fd, 0, SEEK_SET) < 0) {
+        retval = -EIO;
+        goto defer;
+    }
+
+    if (read(fd, text, length) < length) {
+        retval = -EIO;
+        goto defer;
+    }
+
+    text[length] = '\0';
+    retval = 0;
+
+defer:
+    free(text_file_path);
+    if (fd >= 0) close(fd);
+    return retval;
+}