Remove some and deny new indexing and slicing

src/chat.rs

@@ -907,11 +907,10 @@ impl Chat {
 
                     // the whole list of messages referenced may be huge;
                     // only use the oldest and and the parent message
-                    let parent_references = if let Some(n) = parent_references.find(' ') {
-                        &parent_references[0..n]
-                    } else {
-                        &parent_references
-                    };
+                    let parent_references = parent_references
+                        .find(' ')
+                        .and_then(|n| parent_references.get(..n))
+                        .unwrap_or(&parent_references);
 
                     if !parent_references.is_empty() && !parent_rfc724_mid.is_empty() {
                         // angle brackets are added by the mimefactory later

src/configure/mod.rs

@@ -1,7 +1,5 @@
 //! Email accounts autoconfiguration process module
 
-#![forbid(clippy::indexing_slicing)]
-
 mod auto_mozilla;
 mod auto_outlook;
 mod read_url;

src/contact.rs

@@ -1,7 +1,5 @@
 //! Contacts module
 
-#![forbid(clippy::indexing_slicing)]
-
 use async_std::path::PathBuf;
 use deltachat_derive::*;
 use itertools::Itertools;

src/dc_receive_imf.rs

@@ -1512,6 +1512,7 @@ async fn create_adhoc_grp_id(context: &Context, member_ids: &[u32]) -> String {
     hex_hash(&members)
 }
 
+#[allow(clippy::indexing_slicing)]
 fn hex_hash(s: impl AsRef<str>) -> String {
     let bytes = s.as_ref().as_bytes();
     let result = Sha256::digest(bytes);
@@ -1564,7 +1565,7 @@ async fn search_chat_ids_by_contact_ids(
                             matches = 0;
                             mismatches = 0;
                         }
-                        if matches < contact_ids.len() && contact_id == contact_ids[matches] {
+                        if contact_ids.get(matches) == Some(&contact_id) {
                             matches += 1;
                         } else {
                             mismatches += 1;
@@ -1692,10 +1693,11 @@ async fn check_verified_properties(
 
 fn set_better_msg(mime_parser: &mut MimeMessage, better_msg: impl AsRef<str>) {
     let msg = better_msg.as_ref();
-    if !msg.is_empty() && !mime_parser.parts.is_empty() {
-        let part = &mut mime_parser.parts[0];
-        if part.typ == Viewtype::Text {
-            part.msg = msg.to_string();
+    if !msg.is_empty() {
+        if let Some(part) = mime_parser.parts.get_mut(0) {
+            if part.typ == Viewtype::Text {
+                part.msg = msg.to_string();
+            }
         }
     }
 }

src/dc_tools.rs

@@ -22,6 +22,7 @@ pub(crate) fn dc_exactly_one_bit_set(v: i32) -> bool {
 
 /// Shortens a string to a specified length and adds "[...]" to the
 /// end of the shortened string.
+#[allow(clippy::indexing_slicing)]
 pub(crate) fn dc_truncate(buf: &str, approx_chars: usize) -> Cow<str> {
     let ellipse = "[...]";
 
@@ -54,6 +55,7 @@ const COLORS: [u32; 16] = [
     0xf2_30_30, 0x39_b2_49, 0xbb_24_3b, 0x96_40_78, 0x66_87_4f, 0x30_8a_b9, 0x12_7e_d0, 0xbe_45_0c,
 ];
 
+#[allow(clippy::indexing_slicing)]
 pub(crate) fn dc_str_to_color(s: impl AsRef<str>) -> u32 {
     let str_lower = s.as_ref().to_lowercase();
     let mut checksum = 0;
@@ -198,7 +200,7 @@ fn encode_66bits_as_base64(v1: u32, v2: u32, fill: u32) -> String {
 pub(crate) fn dc_create_outgoing_rfc724_mid(grpid: Option<&str>, from_addr: &str) -> String {
     let hostname = from_addr
         .find('@')
-        .map(|k| &from_addr[k..])
+        .and_then(|k| from_addr.get(k..))
         .unwrap_or("@nohost");
     match grpid {
         Some(grpid) => format!("Gr.{}.{}{}", grpid, dc_create_id(), hostname),

src/e2ee.rs

@@ -187,24 +187,23 @@ fn get_autocrypt_mime<'a, 'b>(mail: &'a ParsedMail<'b>) -> Result<&'a ParsedMail
         "Not a multipart/encrypted message: {}",
         mail.ctype.mimetype
     );
-    ensure!(
-        mail.subparts.len() == 2,
-        "Invalid Autocrypt Level 1 Mime Parts"
-    );
-
-    ensure!(
-        mail.subparts[0].ctype.mimetype == "application/pgp-encrypted",
-        "Invalid Autocrypt Level 1 version part: {:?}",
-        mail.subparts[0].ctype,
-    );
+    if let [first_part, second_part] = &mail.subparts[..] {
+        ensure!(
+            first_part.ctype.mimetype == "application/pgp-encrypted",
+            "Invalid Autocrypt Level 1 version part: {:?}",
+            first_part.ctype,
+        );
 
-    ensure!(
-        mail.subparts[1].ctype.mimetype == "application/octet-stream",
-        "Invalid Autocrypt Level 1 encrypted part: {:?}",
-        mail.subparts[1].ctype
-    );
+        ensure!(
+            second_part.ctype.mimetype == "application/octet-stream",
+            "Invalid Autocrypt Level 1 encrypted part: {:?}",
+            second_part.ctype
+        );
 
-    Ok(&mail.subparts[1])
+        Ok(second_part)
+    } else {
+        bail!("Invalid Autocrypt Level 1 Mime Parts")
+    }
 }
 
 async fn decrypt_if_autocrypt_message<'a>(
@@ -267,6 +266,7 @@ async fn decrypt_part(
     Ok(None)
 }
 
+#[allow(clippy::indexing_slicing)]
 fn has_decrypted_pgp_armor(input: &[u8]) -> bool {
     if let Some(index) = input.iter().position(|b| *b > b' ') {
         if input.len() - index > 26 {

src/imap/mod.rs

@@ -3,8 +3,6 @@
 //! uses [async-email/async-imap](https://github.com/async-email/async-imap)
 //! to implement connect, fetch, delete functionality with standard IMAP servers.
 
-#![forbid(clippy::indexing_slicing)]
-
 use std::collections::BTreeMap;
 
 use async_imap::{

src/imex.rs

@@ -178,10 +178,11 @@ async fn do_initiate_key_transfer(context: &Context) -> Result<String> {
 ///
 /// The `passphrase` must be at least 2 characters long.
 pub async fn render_setup_file(context: &Context, passphrase: &str) -> Result<String> {
-    ensure!(
-        passphrase.len() >= 2,
-        "Passphrase must be at least 2 chars long."
-    );
+    let passphrase_begin = if let Some(passphrase_begin) = passphrase.get(..2) {
+        passphrase_begin
+    } else {
+        bail!("Passphrase must be at least 2 chars long.");
+    };
     let private_key = SignedSecretKey::load_self(context).await?;
     let ac_headers = match context.get_config_bool(Config::E2eeEnabled).await {
         false => None,
@@ -196,7 +197,7 @@ pub async fn render_setup_file(context: &Context, passphrase: &str) -> Result<St
             "Passphrase-Format: numeric9x4\r\n",
             "Passphrase-Begin: {}"
         ),
-        &passphrase[..2]
+        passphrase_begin
     );
     let pgp_msg = encr.replace("-----BEGIN PGP MESSAGE-----", &replacement);
 

src/lib.rs

@@ -1,5 +1,10 @@
 #![forbid(unsafe_code)]
-#![deny(clippy::correctness, missing_debug_implementations, clippy::all)]
+#![deny(
+    clippy::correctness,
+    missing_debug_implementations,
+    clippy::all,
+    clippy::indexing_slicing
+)]
 #![allow(clippy::match_bool)]
 
 #[macro_use]

src/mimeparser.rs

@@ -239,6 +239,7 @@ impl MimeMessage {
     ///
     /// Delta Chat sends attachments, such as images, in two-part messages, with the first message
     /// containing an explanation. If such a message is detected, first part can be safely dropped.
+    #[allow(clippy::indexing_slicing)]
     fn squash_attachment_parts(&mut self) {
         if let [textpart, filepart] = &self.parts[..] {
             let need_drop = {
@@ -272,34 +273,34 @@ impl MimeMessage {
     fn parse_attachments(&mut self) {
         // Attachment messages should be squashed into a single part
         // before calling this function.
-        if self.parts.len() == 1 {
-            if self.parts[0].typ == Viewtype::Audio
-                && self.get(HeaderDef::ChatVoiceMessage).is_some()
-            {
-                let part_mut = &mut self.parts[0];
-                part_mut.typ = Viewtype::Voice;
+        if self.parts.len() != 1 {
+            return;
+        }
+
+        if let Some(mut part) = self.parts.pop() {
+            if part.typ == Viewtype::Audio && self.get(HeaderDef::ChatVoiceMessage).is_some() {
+                part.typ = Viewtype::Voice;
             }
-            if self.parts[0].typ == Viewtype::Image {
+            if part.typ == Viewtype::Image {
                 if let Some(value) = self.get(HeaderDef::ChatContent) {
                     if value == "sticker" {
-                        let part_mut = &mut self.parts[0];
-                        part_mut.typ = Viewtype::Sticker;
+                        part.typ = Viewtype::Sticker;
                     }
                 }
             }
-            let part = &self.parts[0];
             if part.typ == Viewtype::Audio
                 || part.typ == Viewtype::Voice
                 || part.typ == Viewtype::Video
             {
                 if let Some(field_0) = self.get(HeaderDef::ChatDuration) {
                     let duration_ms = field_0.parse().unwrap_or_default();
                     if duration_ms > 0 && duration_ms < 24 * 60 * 60 * 1000 {
-                        let part_mut = &mut self.parts[0];
-                        part_mut.param.set_int(Param::Duration, duration_ms);
+                        part.param.set_int(Param::Duration, duration_ms);
                     }
                 }
             }
+
+            self.parts.push(part);
         }
     }
 
@@ -321,12 +322,11 @@ impl MimeMessage {
                 }
             }
             if prepend_subject {
-                let subj = if let Some(n) = subject.find('[') {
-                    &subject[0..n]
-                } else {
-                    subject
-                }
-                .trim();
+                let subj = subject
+                    .find('[')
+                    .and_then(|n| subject.get(..n))
+                    .unwrap_or(subject)
+                    .trim();
 
                 if !subj.is_empty() {
                     for part in self.parts.iter_mut() {
@@ -384,8 +384,7 @@ impl MimeMessage {
             Some(AvatarAction::Delete)
         } else {
             let mut i = 0;
-            while i != self.parts.len() {
-                let part = &mut self.parts[i];
+            while let Some(part) = self.parts.get_mut(i) {
                 if let Some(part_filename) = &part.org_filename {
                     if part_filename == &header_value {
                         if let Some(blob) = part.param.get(Param::File) {
@@ -770,16 +769,11 @@ impl MimeMessage {
     }
 
     pub fn repl_msg_by_error(&mut self, error_msg: impl AsRef<str>) {
-        if self.parts.is_empty() {
-            return;
+        if let Some(part) = self.parts.first_mut() {
+            part.typ = Viewtype::Text;
+            part.msg = format!("[{}]", error_msg.as_ref());
+            self.parts.truncate(1);
         }
-
-        let part = &mut self.parts[0];
-        part.typ = Viewtype::Text;
-        part.msg = format!("[{}]", error_msg.as_ref());
-        self.parts.truncate(1);
-
-        assert_eq!(self.parts.len(), 1);
     }
 
     pub fn get_rfc724_mid(&self) -> Option<String> {
@@ -830,7 +824,11 @@ impl MimeMessage {
         report: &mailparse::ParsedMail<'_>,
     ) -> Result<Option<Report>> {
         // parse as mailheaders
-        let report_body = report.subparts[1].get_body_raw()?;
+        let report_body = if let Some(subpart) = report.subparts.get(1) {
+            subpart.get_body_raw()?
+        } else {
+            bail!("Report does not have second MIME part");
+        };
         let (report_fields, _) = mailparse::parse_headers(&report_body)?;
 
         // must be present
@@ -908,6 +906,7 @@ impl MimeMessage {
     /// Some providers like GMX and Yahoo do not send standard NDNs (Non Delivery notifications).
     /// If you improve heuristics here you might also have to change prefetch_should_download() in imap/mod.rs.
     /// Also you should add a test in dc_receive_imf.rs (there already are lots of test_parse_ndn_* tests).
+    #[allow(clippy::indexing_slicing)]
     async fn heuristically_parse_ndn(&mut self, context: &Context) -> Option<()> {
         let maybe_ndn = if let Some(from) = self.get(HeaderDef::From_) {
             let from = from.to_ascii_lowercase();
@@ -966,11 +965,10 @@ impl MimeMessage {
         if let Some(failure_report) = &self.failure_report {
             let error = parts.iter().find(|p| p.typ == Viewtype::Text).map(|p| {
                 let msg = &p.msg;
-                match msg.find("\n--- ") {
-                    Some(footer_start) => &msg[..footer_start],
-                    None => msg,
-                }
-                .trim()
+                msg.find("\n--- ")
+                    .and_then(|footer_start| msg.get(..footer_start))
+                    .unwrap_or(msg)
+                    .trim()
             });
             message::handle_ndn(context, failure_report, error).await
         }
@@ -1036,6 +1034,7 @@ pub(crate) struct FailureReport {
     pub failed_recipient: Option<String>,
 }
 
+#[allow(clippy::indexing_slicing)]
 pub(crate) fn parse_message_ids(ids: &str) -> Result<Vec<String>> {
     // take care with mailparse::msgidparse() that is pretty untolerant eg. wrt missing `<` or `>`
     let mut msgids = Vec::new();

src/param.rs

@@ -171,7 +171,7 @@ impl str::FromStr for Params {
             let key = key.unwrap_or_default().trim();
             let value = value.unwrap_or_default().trim();
 
-            if let Some(key) = Param::from_u8(key.as_bytes()[0]) {
+            if let Some(key) = key.as_bytes().first().and_then(|key| Param::from_u8(*key)) {
                 inner.insert(key, value.to_string());
             } else {
                 bail!("Unknown key: {}", key);

src/pgp.rs

@@ -365,11 +365,13 @@ pub async fn symm_decrypt<T: std::io::Read + std::io::Seek>(
         let decryptor = enc_msg.decrypt_with_password(|| passphrase)?;
 
         let msgs = decryptor.collect::<pgp::errors::Result<Vec<_>>>()?;
-        ensure!(!msgs.is_empty(), "No valid messages found");
-
-        match msgs[0].get_content()? {
-            Some(content) => Ok(content),
-            None => bail!("Decrypted message is empty"),
+        if let Some(msg) = msgs.first() {
+            match msg.get_content()? {
+                Some(content) => Ok(content),
+                None => bail!("Decrypted message is empty"),
+            }
+        } else {
+            bail!("No valid messages found")
         }
     })
     .await