6c201db005
Checks for the suspicious use of OpenOptions::create() without an explicit OpenOptions::truncate(). create() alone will either create a new file or open an existing file. If the file already exists, it will be overwritten when written to, but the file will not be truncated by default. If less data is written to the file than it already contains, the remainder of the file will remain unchanged, and the end of the file will contain old data. In most cases, one should either use `create_new` to ensure the file is created from scratch, or ensure `truncate` is called so that the truncation behaviour is explicit. `truncate(true)` will ensure the file is entirely overwritten with new data, whereas `truncate(false)` will explicitely keep the default behavior. ```rust use std::fs::OpenOptions; OpenOptions::new().create(true).truncate(true); ```
143 lines
3.3 KiB
Rust
143 lines
3.3 KiB
Rust
#![allow(unused)]
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#![warn(clippy::seek_to_start_instead_of_rewind)]
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use std::fs::OpenOptions;
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use std::io::{Read, Seek, SeekFrom, Write};
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struct StructWithSeekMethod {}
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impl StructWithSeekMethod {
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fn seek(&mut self, from: SeekFrom) {}
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}
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trait MySeekTrait {
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fn seek(&mut self, from: SeekFrom) {}
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}
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struct StructWithSeekTrait {}
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impl MySeekTrait for StructWithSeekTrait {}
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// This should NOT trigger clippy warning because
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// StructWithSeekMethod does not implement std::io::Seek;
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fn seek_to_start_false_method(t: &mut StructWithSeekMethod) {
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t.seek(SeekFrom::Start(0));
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}
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// This should NOT trigger clippy warning because
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// StructWithSeekMethod does not implement std::io::Seek;
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fn seek_to_start_method_owned_false(mut t: StructWithSeekMethod) {
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t.seek(SeekFrom::Start(0));
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}
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// This should NOT trigger clippy warning because
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// StructWithSeekMethod does not implement std::io::Seek;
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fn seek_to_start_false_trait(t: &mut StructWithSeekTrait) {
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t.seek(SeekFrom::Start(0));
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}
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// This should NOT trigger clippy warning because
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// StructWithSeekMethod does not implement std::io::Seek;
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fn seek_to_start_false_trait_owned(mut t: StructWithSeekTrait) {
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t.seek(SeekFrom::Start(0));
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}
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// This should NOT trigger clippy warning because
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// StructWithSeekMethod does not implement std::io::Seek;
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fn seek_to_start_false_trait_bound<T: MySeekTrait>(t: &mut T) {
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t.seek(SeekFrom::Start(0));
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}
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// This should trigger clippy warning
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fn seek_to_start<T: Seek>(t: &mut T) {
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t.rewind();
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}
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// This should trigger clippy warning
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fn owned_seek_to_start<T: Seek>(mut t: T) {
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t.rewind();
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}
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// This should NOT trigger clippy warning because
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// it does not seek to start
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fn seek_to_5<T: Seek>(t: &mut T) {
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t.seek(SeekFrom::Start(5));
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}
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// This should NOT trigger clippy warning because
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// it does not seek to start
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fn seek_to_end<T: Seek>(t: &mut T) {
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t.seek(SeekFrom::End(0));
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}
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// This should NOT trigger clippy warning because
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// expr is used here
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fn seek_to_start_in_let<T: Seek>(t: &mut T) {
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let a = t.seek(SeekFrom::Start(0)).unwrap();
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}
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fn main() {
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let mut f = OpenOptions::new()
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.write(true)
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.read(true)
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.create(true)
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.truncate(true)
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.open("foo.txt")
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.unwrap();
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let mut my_struct_trait = StructWithSeekTrait {};
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seek_to_start_false_trait_bound(&mut my_struct_trait);
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let hello = "Hello!\n";
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write!(f, "{hello}").unwrap();
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seek_to_5(&mut f);
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seek_to_end(&mut f);
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seek_to_start(&mut f);
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let mut buf = String::new();
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f.read_to_string(&mut buf).unwrap();
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assert_eq!(&buf, hello);
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}
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#[clippy::msrv = "1.54"]
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fn msrv_1_54() {
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let mut f = OpenOptions::new()
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.write(true)
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.read(true)
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.create(true)
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.truncate(true)
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.open("foo.txt")
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.unwrap();
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let hello = "Hello!\n";
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write!(f, "{hello}").unwrap();
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f.seek(SeekFrom::Start(0));
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let mut buf = String::new();
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f.read_to_string(&mut buf).unwrap();
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assert_eq!(&buf, hello);
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}
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#[clippy::msrv = "1.55"]
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fn msrv_1_55() {
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let mut f = OpenOptions::new()
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.write(true)
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.read(true)
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.create(true)
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.truncate(true)
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.open("foo.txt")
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.unwrap();
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let hello = "Hello!\n";
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write!(f, "{hello}").unwrap();
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f.rewind();
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let mut buf = String::new();
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f.read_to_string(&mut buf).unwrap();
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assert_eq!(&buf, hello);
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}
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