git: f9e79facf874 - main - sh: Implement simple parameter expansion in PS1 and PS2
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Date: Fri, 07 Nov 2025 22:41:09 UTC
The branch main has been updated by jilles:
URL: https://cgit.FreeBSD.org/src/commit/?id=f9e79facf874567f25147b24863e5198164e8d04
commit f9e79facf874567f25147b24863e5198164e8d04
Author: Matthew Phillips <matthew@matthewphillips.info>
AuthorDate: 2025-10-12 19:27:34 +0000
Commit: Jilles Tjoelker <jilles@FreeBSD.org>
CommitDate: 2025-11-07 22:35:18 +0000
sh: Implement simple parameter expansion in PS1 and PS2
This change follows a localized approach within getprompt() and avoids
full parser reentry. While this means we don't support advanced
expansions like ${parameter#pattern}, it provides POSIX-compliant basic
parameter expansion without the complexity of making the parser
reentrant. This is sufficient for the vast majority of use cases.
PR: 46441
---
bin/sh/parser.c | 126 +++++++++++++++++++++++++++++++++++++-
bin/sh/tests/parser/Makefile | 6 ++
bin/sh/tests/parser/ps1-expand1.0 | 7 +++
bin/sh/tests/parser/ps1-expand2.0 | 7 +++
bin/sh/tests/parser/ps1-expand3.0 | 8 +++
bin/sh/tests/parser/ps1-expand4.0 | 8 +++
bin/sh/tests/parser/ps1-expand5.0 | 8 +++
bin/sh/tests/parser/ps2-expand1.0 | 12 ++++
8 files changed, 181 insertions(+), 1 deletion(-)
diff --git a/bin/sh/parser.c b/bin/sh/parser.c
index 0c1b7a91c257..3e42d41caec4 100644
--- a/bin/sh/parser.c
+++ b/bin/sh/parser.c
@@ -55,6 +55,8 @@
#include "show.h"
#include "eval.h"
#include "exec.h" /* to check for special builtins */
+#include "main.h"
+#include "jobs.h"
#ifndef NO_HISTORY
#include "myhistedit.h"
#endif
@@ -2050,7 +2052,129 @@ getprompt(void *unused __unused)
* Format prompt string.
*/
for (i = 0; (i < PROMPTLEN - 1) && (*fmt != '\0'); i++, fmt++) {
- if (*fmt != '\\') {
+ if (*fmt == '$') {
+ const char *varname_start, *varname_end, *value;
+ char varname[256];
+ int namelen, braced = 0;
+
+ fmt++; /* Skip the '$' */
+
+ /* Check for ${VAR} syntax */
+ if (*fmt == '{') {
+ braced = 1;
+ fmt++;
+ }
+
+ varname_start = fmt;
+
+ /* Extract variable name */
+ if (is_digit(*fmt)) {
+ /* Positional parameter: $0, $1, etc. */
+ fmt++;
+ varname_end = fmt;
+ } else if (is_special(*fmt)) {
+ /* Special parameter: $?, $!, $$, etc. */
+ fmt++;
+ varname_end = fmt;
+ } else if (is_name(*fmt)) {
+ /* Regular variable name */
+ do
+ fmt++;
+ while (is_in_name(*fmt));
+ varname_end = fmt;
+ } else {
+ /*
+ * Not a valid variable reference.
+ * Output literal '$'.
+ */
+ ps[i] = '$';
+ if (braced && i < PROMPTLEN - 2)
+ ps[++i] = '{';
+ fmt = varname_start - 1;
+ continue;
+ }
+
+ namelen = varname_end - varname_start;
+ if (namelen == 0 || namelen >= (int)sizeof(varname)) {
+ /* Invalid or too long, output literal */
+ ps[i] = '$';
+ fmt = varname_start - 1;
+ continue;
+ }
+
+ /* Copy variable name */
+ memcpy(varname, varname_start, namelen);
+ varname[namelen] = '\0';
+
+ /* Handle closing brace for ${VAR} */
+ if (braced) {
+ if (*fmt == '}') {
+ fmt++;
+ } else {
+ /* Missing closing brace, treat as literal */
+ ps[i] = '$';
+ if (i < PROMPTLEN - 2)
+ ps[++i] = '{';
+ fmt = varname_start - 1;
+ continue;
+ }
+ }
+
+ /* Look up the variable */
+ if (namelen == 1 && is_digit(*varname)) {
+ /* Positional parameters - check digits FIRST */
+ int num = *varname - '0';
+ if (num == 0)
+ value = arg0 ? arg0 : "";
+ else if (num > 0 && num <= shellparam.nparam)
+ value = shellparam.p[num - 1];
+ else
+ value = "";
+ } else if (namelen == 1 && is_special(*varname)) {
+ /* Special parameters */
+ char valbuf[20];
+ int num;
+
+ switch (*varname) {
+ case '$':
+ num = rootpid;
+ break;
+ case '?':
+ num = exitstatus;
+ break;
+ case '#':
+ num = shellparam.nparam;
+ break;
+ case '!':
+ num = backgndpidval();
+ break;
+ default:
+ num = 0;
+ break;
+ }
+ snprintf(valbuf, sizeof(valbuf), "%d", num);
+ value = valbuf;
+ } else {
+ /* Regular variables */
+ value = lookupvar(varname);
+ if (value == NULL)
+ value = "";
+ }
+
+ /* Copy value to output, respecting buffer size */
+ while (*value != '\0' && i < PROMPTLEN - 1) {
+ ps[i++] = *value++;
+ }
+
+ /*
+ * Adjust fmt and i for the loop increment.
+ * fmt will be incremented by the for loop,
+ * so position it one before where we want.
+ */
+ fmt--;
+ i--;
+ continue;
+ } else if (*fmt != '\\') {
ps[i] = *fmt;
continue;
}
diff --git a/bin/sh/tests/parser/Makefile b/bin/sh/tests/parser/Makefile
index afeb604710e4..c22af5414526 100644
--- a/bin/sh/tests/parser/Makefile
+++ b/bin/sh/tests/parser/Makefile
@@ -86,6 +86,12 @@ ${PACKAGE}FILES+= only-redir2.0
${PACKAGE}FILES+= only-redir3.0
${PACKAGE}FILES+= only-redir4.0
${PACKAGE}FILES+= pipe-not1.0
+${PACKAGE}FILES+= ps1-expand1.0
+${PACKAGE}FILES+= ps1-expand2.0
+${PACKAGE}FILES+= ps1-expand3.0
+${PACKAGE}FILES+= ps1-expand4.0
+${PACKAGE}FILES+= ps1-expand5.0
+${PACKAGE}FILES+= ps2-expand1.0
${PACKAGE}FILES+= set-v1.0 set-v1.0.stderr
${PACKAGE}FILES+= var-assign1.0
diff --git a/bin/sh/tests/parser/ps1-expand1.0 b/bin/sh/tests/parser/ps1-expand1.0
new file mode 100644
index 000000000000..351e6437a023
--- /dev/null
+++ b/bin/sh/tests/parser/ps1-expand1.0
@@ -0,0 +1,7 @@
+# Test simple variable expansion in PS1
+testvar=abcdef
+output=$(testvar=abcdef PS1='$testvar:' ENV=/dev/null ${SH} +m -i </dev/null 2>&1)
+case $output in
+*abcdef*) exit 0 ;;
+*) echo "Expected 'abcdef' in prompt output"; exit 1 ;;
+esac
diff --git a/bin/sh/tests/parser/ps1-expand2.0 b/bin/sh/tests/parser/ps1-expand2.0
new file mode 100644
index 000000000000..ed31a7c17136
--- /dev/null
+++ b/bin/sh/tests/parser/ps1-expand2.0
@@ -0,0 +1,7 @@
+# Test braced variable expansion in PS1
+testvar=xyz123
+output=$(testvar=xyz123 PS1='prefix-${testvar}-suffix:' ENV=/dev/null ${SH} +m -i </dev/null 2>&1)
+case $output in
+*xyz123*) exit 0 ;;
+*) echo "Expected 'xyz123' in prompt output"; exit 1 ;;
+esac
diff --git a/bin/sh/tests/parser/ps1-expand3.0 b/bin/sh/tests/parser/ps1-expand3.0
new file mode 100644
index 000000000000..0b6270c300ff
--- /dev/null
+++ b/bin/sh/tests/parser/ps1-expand3.0
@@ -0,0 +1,8 @@
+# Test special parameter $$ (PID) in PS1
+output=$(PS1='pid:$$:' ENV=/dev/null ${SH} +m -i </dev/null 2>&1)
+# Check that output contains "pid:" followed by a number (not literal $$)
+case $output in
+*pid:\$\$:*) echo "PID not expanded, got literal \$\$"; exit 1 ;;
+*pid:[0-9]*) exit 0 ;;
+*) echo "Expected PID after 'pid:' in output"; exit 1 ;;
+esac
diff --git a/bin/sh/tests/parser/ps1-expand4.0 b/bin/sh/tests/parser/ps1-expand4.0
new file mode 100644
index 000000000000..623c52707eec
--- /dev/null
+++ b/bin/sh/tests/parser/ps1-expand4.0
@@ -0,0 +1,8 @@
+# Test special parameter $? (exit status) in PS1
+output=$(PS1='status:$?:' ENV=/dev/null ${SH} +m -i </dev/null 2>&1)
+# Should start with exit status 0
+case $output in
+*status:\$?:*) echo "Exit status not expanded, got literal \$?"; exit 1 ;;
+*status:0:*) exit 0 ;;
+*) echo "Expected 'status:0:' in initial prompt"; exit 1 ;;
+esac
diff --git a/bin/sh/tests/parser/ps1-expand5.0 b/bin/sh/tests/parser/ps1-expand5.0
new file mode 100644
index 000000000000..73fe3ba5a3d5
--- /dev/null
+++ b/bin/sh/tests/parser/ps1-expand5.0
@@ -0,0 +1,8 @@
+# Test positional parameter $0 in PS1
+output=$(PS1='shell:$0:' ENV=/dev/null ${SH} +m -i </dev/null 2>&1)
+# $0 should contain the shell name/path
+case $output in
+*shell:\$0:*) echo "Positional parameter not expanded, got literal \$0"; exit 1 ;;
+*shell:*sh*:*) exit 0 ;;
+*) echo "Expected shell name after 'shell:' in output"; exit 1 ;;
+esac
diff --git a/bin/sh/tests/parser/ps2-expand1.0 b/bin/sh/tests/parser/ps2-expand1.0
new file mode 100644
index 000000000000..f0a3a77ded1c
--- /dev/null
+++ b/bin/sh/tests/parser/ps2-expand1.0
@@ -0,0 +1,12 @@
+# Test variable expansion in PS2 (continuation prompt)
+testvar=continue
+# Send incomplete command (backslash at end) to trigger PS2
+output=$(testvar=continue PS2='$testvar>' ENV=/dev/null ${SH} +m -i <<EOF 2>&1
+echo \\
+done
+EOF
+)
+case $output in
+*continue\>*) exit 0 ;;
+*) echo "Expected 'continue>' in PS2 output"; exit 1 ;;
+esac