From 6cb42ec21be72ffe70d2970aa996cdb041c8dd9f Mon Sep 17 00:00:00 2001
From: Timothy Warren <twarren@nabancard.com>
Date: Thu, 17 Sep 2020 16:08:33 -0400
Subject: [PATCH] First commit, first part of the tutorial

---
 .gitignore    |   1 +
 Cargo.toml    |   9 ++++++++
 data.sqlite   | Bin 0 -> 16384 bytes
 src/error.rs  |  24 ++++++++++++++++++++
 src/header.rs |  61 ++++++++++++++++++++++++++++++++++++++++++++++++++
 src/lib.rs    |   2 ++
 src/main.rs   |  19 ++++++++++++++++
 7 files changed, 116 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 Cargo.toml
 create mode 100644 data.sqlite
 create mode 100644 src/error.rs
 create mode 100644 src/header.rs
 create mode 100644 src/lib.rs
 create mode 100644 src/main.rs

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..ea8c4bf
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/target
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..7f8939f
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,9 @@
+[package]
+name = "sqlite-parser"
+version = "0.1.0"
+authors = ["Timothy Warren <tim@timshomepage.net>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/data.sqlite b/data.sqlite
new file mode 100644
index 0000000000000000000000000000000000000000..deaa23c0cb49c50eaffda25afff541c540bf2829
GIT binary patch
literal 16384
zcmeI(&q~8E90%|uoqsmadKo(jKM~QPD55tnn-XNY)mb}mr;%xtLEFu)1wHy=zJgES
zYlsIACe<ArcomWF50doPCQb9{DU@EEHwUSvn_&{El=j#X<DAuq7-Pbef+>^W=3qLX
zT>GgNY<r&;+&AVdzA^X2eKrjO0uX=z1Rwwb2tWV=5P$##An<DfZD+Q!xyie!>W6xK
z7n)6QZ>;Y!9bZkSg(F|q14%*suqkP(??$X5y=6vL9|fPQl*|0_Hos>!)`>0R+h}`+
zHcDh-a7_&_kjK&|?<^p%(`-`PZ?x)umriAu>Yd=M;hE7b=>^pB8s{Ckm5;PjQXnsb
z&s0Zh5axNQx-Mob2W8F%@wLAHdQ_FA!#wZV*?YUTb`12q#a=K)xKGS|F%<#=5P$##
zAOHafKmY;|fB*y_0D(U!uq+B}wc1u$NQYVcpyE-#rteiW3ibBYFk0aSwzlIB`#MRf
zrN%l=YDu0&HnCkwW>vy{W$wGF5D<U>1Rwwb2tWV=5P$##AOHaf{3C%GhjSqur&zS#
q|GC}&WB31$-Y=E{0SG_<0uX=z1Rwwb2tWV=5U>LC+$r<??}QJ}LU_{v

literal 0
HcmV?d00001

diff --git a/src/error.rs b/src/error.rs
new file mode 100644
index 0000000..2c6db91
--- /dev/null
+++ b/src/error.rs
@@ -0,0 +1,24 @@
+use std::fmt;
+
+/// Representation of our possible errors.
+/// Each variant will contain a string for more
+/// detailed information
+#[derive(Debug)]
+pub enum Error {
+    /// An error related to the first 16 bytes
+    HeaderString(String),
+    /// An error parsing the page size
+    InvalidPageSize(String),
+}
+
+impl fmt::Display for Error {
+    /// This will be called whenever we print
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Self::HeaderString(v) => write!(f, "Unexpected bytes at start of file, expected the magic string 'SQLite format 3\u{0}', found {:?}", v),
+            Self::InvalidPageSize(msg) => write!(f, "Invalid page size, {}", msg),
+        }
+    }
+}
+
+impl std::error::Error for Error {}
\ No newline at end of file
diff --git a/src/header.rs b/src/header.rs
new file mode 100644
index 0000000..d7785ea
--- /dev/null
+++ b/src/header.rs
@@ -0,0 +1,61 @@
+use crate::error::Error;
+use std::convert::{TryFrom, TryInto};
+
+static HEADER_STRING: &[u8] = &[
+    //S q   l   i    t    e    ` ` f    o    r    m    a   t    ` ` 3   \u{0}
+    83, 81, 76, 105, 116, 101, 32, 102, 111, 114, 109, 97, 116, 32, 51, 0,
+];
+
+/// This struct will wrap our 32bit number allowing us
+/// to control how it gets used later.
+#[derive(Debug)]
+pub struct PageSize(u32);
+
+impl TryFrom<u16> for PageSize {
+    type Error = Error;
+
+    fn try_from(v: u16) -> Result<PageSize, Self::Error> {
+        match v {
+            // Special case for the largest page size
+            1 => Ok(PageSize(65_536u32)),
+
+            // < 512, != 1
+            0 | 2..=511 => Err(Error::InvalidPageSize(format!(
+                "value must be >= 512, found: {}",
+                v
+            ))),
+
+            _ => {
+                if v.is_power_of_two() {
+                    Ok(PageSize(v as u32))
+                } else {
+                    Err(Error::InvalidPageSize(format!(
+                        "value must be a power of 2, found: {}",
+                        v
+                    )))
+                }
+            }
+        }
+    }
+}
+
+/// Validate that the bytes provided match the special string
+/// at the start of Sqlite3 files
+pub fn validate_magic_string(bytes: &[u8]) -> Result<(), Error> {
+    let buf = &bytes[0..16];
+    if buf != HEADER_STRING {
+        return Err(Error::HeaderString(String::from_utf8_lossy(buf).to_string()));
+    }
+
+    Ok(())
+}
+
+/// Attempt to generate the appropriate `PageSize` struct
+pub fn parse_page_size(bytes: &[u8]) -> Result<PageSize, Error> {
+    // Convert into array, and convert error if needed, so that the `?` operator works
+    let page_size_bytes: [u8; 2] = bytes[16..18].try_into().map_err(|_| {
+       Error::InvalidPageSize(format!("expected a 2 byte slice, found: {:?}", bytes))
+    })?;
+
+    u16::from_be_bytes(page_size_bytes).try_into()
+}
\ No newline at end of file
diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..f8da16c
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,2 @@
+pub mod error;
+pub mod header;
\ No newline at end of file
diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 0000000..19e7056
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,19 @@
+use sqlite_parser::{
+    header::{validate_magic_string, parse_page_size},
+    error::Error,
+};
+use std::fs::read;
+
+fn main() -> Result<(), Error> {
+    // first, read in all the bytes of our file
+    // using unwrap to just panic if this fails
+    let contents = read("data.sqlite").unwrap();
+
+    validate_magic_string(&contents)?;
+
+    let page_size = parse_page_size(&contents)?;
+
+    println!("{:?}", page_size);
+
+    Ok(())
+}