Add shell script formatter

Leverage shfmt as the standard formatter for shell scripts in this repo.
- add `.editorconfig` with formatting rules and apply shfmt in
  .ci/check-format.sh.
- update CONTRIBUTING.md with usage instructions (all contributors
  should use it to ensure consistent shell script style).

The early exit behavior (set -e) in .ci/check-format.sh has been removed
to allow collecting all formatting mismatches in a single run. The
script’s exit code is now the sum of the line-level mismatch count from
clang-format-18 and the file-level mismatch count from shfmt, which
should be 0 if all files are properly formatted.

Author: ChinYikMing

.ci/check-format.sh

@@ -1,14 +1,24 @@
 #!/usr/bin/env bash
 
-set -e -u -o pipefail
+# The -e is not set because we want to get all the mismatch format at once
 
-SOURCES=$(find $(git rev-parse --show-toplevel) | egrep "\.(c|cxx|cpp|h|hpp)\$")
+set -u -o pipefail
 
 set -x
 
-for file in ${SOURCES};
-do
-    clang-format-18 ${file} > expected-format
+REPO_ROOT="$(git rev-parse --show-toplevel)"
+
+C_SOURCES=$(find "${REPO_ROOT}" | egrep "\.(c|cxx|cpp|h|hpp)$")
+for file in ${C_SOURCES}; do
+    clang-format-18 ${file} >expected-format
     diff -u -p --label="${file}" --label="expected coding style" ${file} expected-format
 done
-exit $(clang-format-18 --output-replacements-xml ${SOURCES} | egrep -c "</replacement>")
+C_MISMATCH_LINE_CNT=$(clang-format-18 --output-replacements-xml ${C_SOURCES} | egrep -c "</replacement>")
+
+SH_SOURCES=$(find "${REPO_ROOT}" | egrep "\.sh$")
+for file in ${SH_SOURCES}; do
+    shfmt -d "${file}"
+done
+SH_MISMATCH_FILE_CNT=$(shfmt -l ${SH_SOURCES})
+
+exit $((C_MISMATCH_LINE_CNT + SH_MISMATCH_FILE_CNT))

.editorconfig

@@ -0,0 +1,15 @@
+# Top-level EditorConfig file
+root = true
+
+# Shell script-specific settings
+[*.sh]
+indent_style = space
+indent_size = 4
+end_of_line = lf
+trim_trailing_whitespace = true
+insert_final_newline = true
+function_next_line = true
+switch_case_indent = true
+space_redirects = true
+binary_next_line = true
+keep_padding = true

CONTRIBUTING.md

@@ -44,10 +44,12 @@ However, participation requires adherence to fundamental ground rules:
   This variant should be considered the standard for all documentation efforts.
   For instance, opt for "initialize" over "initialise" and "color" rather than "colour".
 
-Software requirement: [clang-format](https://clang.llvm.org/docs/ClangFormat.html) version 18 or later.
+Software requirement:
+* [clang-format](https://clang.llvm.org/docs/ClangFormat.html) version 18 or later.
+* [shfmt](https://github.com/mvdan/sh).
 
-This repository consistently contains an up-to-date `.clang-format` file with rules that match the explained ones.
-For maintaining a uniform coding style, execute the command `clang-format -i *.{c,h}`.
+This repository consistently contains an up-to-date `.clang-format` file with rules that match the explained ones and uses shell script formatting supported by `shfmt`.
+For maintaining a uniform coding style, execute the command `clang-format -i *.{c,h}` and `shfmt -w $(find . -type f -name "*.sh")`.
 
 ## Coding Style for Modern C
 
@@ -877,22 +879,22 @@ Author: Jim Huang <[email protected]>
 Date:   Mon Feb 24 13:08:32 2025 +0800
 
     Introduce CPU architecture filtering in scheduler
-    
+
     In environments with mixed CPU architectures, it is crucial to ensure
     that an instance runs only on a host with a compatible CPU
     type—preventing, for example, a RISC-V instance from being scheduled on
     an Arm host.
-    
+
     This new scheduler filter enforces that requirement by comparing an
     instance's architecture against the host's allowed architectures. For
     the libvirt driver, the host's guest capabilities are queried, and the
     permitted architectures are recorded in the permitted_instances_types
     list within the host's cpu_info dictionary.
-    
+
     The filter systematically excludes hosts that do not support the
     instance's CPU architecture. Additionally, RISC-V has been added to the
     set of acceptable architectures for scheduling.
-    
+
     Note that the CPU architecture filter is disabled by default.
 ```