Merge pull request #5514 from Luv-Ray/fix-printf-issue5468

`printf`: support %q

src/uu/printf/printf.md

@@ -78,6 +78,9 @@ Fields
             second parameter is min-width, integer
             output below that width is padded with leading zeroes
 
+* `%q`:       ARGUMENT is printed in a format that can be reused as shell input, escaping non-printable
+            characters with the proposed POSIX $'' syntax.
+
 * `%f` or `%F`: decimal floating point value
 * `%e` or `%E`: scientific notation floating point value
 * `%g` or `%G`: shorter of specially interpreted decimal or SciNote floating point value.
@@ -181,6 +184,11 @@ All string fields have a 'max width' parameter
       still be interpreted and not throw a warning, you will have problems if you use this for a
       literal whose code begins with zero, as it will be viewed as in `\\0NNN` form.)
 
+* `%q`:  escaped string - the string in a format that can be reused as input by most shells.
+      Non-printable characters are escaped with the POSIX proposed ‘$''’ syntax,
+      and shell meta-characters are quoted appropriately.
+      This is an equivalent format to ls --quoting=shell-escape output.
+
 #### CHAR SUBSTITUTIONS
 
 The character field does not have a secondary parameter.

src/uucore/src/lib/features/tokenize/sub.rs

@@ -10,6 +10,7 @@
 //! Subs which have numeric field chars make use of the num_format
 //! submodule
 use crate::error::{UError, UResult};
+use crate::quoting_style::{escape_name, QuotingStyle};
 use itertools::{put_back_n, PutBackN};
 use std::error::Error;
 use std::fmt::Display;
@@ -91,7 +92,7 @@ impl Sub {
         // for more dry printing, field characters are grouped
         // in initialization of token.
         let field_type = match field_char {
-            's' | 'b' => FieldType::Strf,
+            's' | 'b' | 'q' => FieldType::Strf,
             'd' | 'i' | 'u' | 'o' | 'x' | 'X' => FieldType::Intf,
             'f' | 'F' => FieldType::Floatf,
             'a' | 'A' => FieldType::CninetyNineHexFloatf,
@@ -189,7 +190,7 @@ impl SubParser {
 
         let mut legal_fields = [
             // 'a', 'A', //c99 hex float implementation not yet complete
-            'b', 'c', 'd', 'e', 'E', 'f', 'F', 'g', 'G', 'i', 'o', 's', 'u', 'x', 'X',
+            'b', 'c', 'd', 'e', 'E', 'f', 'F', 'g', 'G', 'i', 'o', 'q', 's', 'u', 'x', 'X',
         ];
         let mut specifiers = ['h', 'j', 'l', 'L', 't', 'z'];
         legal_fields.sort_unstable();
@@ -260,7 +261,6 @@ impl SubParser {
                 }
                 x if legal_fields.binary_search(&x).is_ok() => {
                     self.field_char = Some(ch);
-                    self.text_so_far.push(ch);
                     break;
                 }
                 x if specifiers.binary_search(&x).is_ok() => {
@@ -331,7 +331,7 @@ impl SubParser {
         if (field_char == 's' && self.min_width_tmp == Some(String::from("0")))
             || (field_char == 'c'
                 && (self.min_width_tmp == Some(String::from("0")) || self.past_decimal))
-            || (field_char == 'b'
+            || ((field_char == 'b' || field_char == 'q')
                 && (self.min_width_tmp.is_some()
                     || self.past_decimal
                     || self.second_field_tmp.is_some()))
@@ -391,6 +391,7 @@ impl Sub {
             // if %s just return arg
             // if %b use UnescapedText module's unescape-fn
             // if %c return first char of arg
+            // if %q return arg which non-printable characters are escaped
             FieldType::Strf | FieldType::Charf => {
                 match pf_arg {
                     Some(arg_string) => {
@@ -404,11 +405,18 @@ impl Sub {
                                 UnescapedText::from_it_core(writer, &mut a_it, true);
                                 None
                             }
-                            // for 'c': get iter of string vals,
+                            'q' => Some(escape_name(
+                                arg_string.as_ref(),
+                                &QuotingStyle::Shell {
+                                    escape: true,
+                                    always_quote: false,
+                                    show_control: false,
+                                },
+                            )),
                             // get opt<char> of first val
                             // and map it to opt<String>
-                            /* 'c' | */
+                            'c' => arg_string.chars().next().map(|x| x.to_string()),
-                            _ => arg_string.chars().next().map(|x| x.to_string()),
+                            _ => unreachable!(),
                         }
                     }
                     None => None,

tests/by-util/test_printf.rs

@@ -112,6 +112,15 @@ fn sub_b_string_handle_escapes() {
         .stdout_only("hello \tworld");
 }
 
+#[test]
+fn sub_b_string_validate_field_params() {
+    new_ucmd!()
+        .args(&["hello %7b", "world"])
+        .run()
+        .stdout_is("hello ")
+        .stderr_is("printf: %7b: invalid conversion specification\n");
+}
+
 #[test]
 fn sub_b_string_ignore_subs() {
     new_ucmd!()
@@ -120,6 +129,31 @@ fn sub_b_string_ignore_subs() {
         .stdout_only("hello world %% %i");
 }
 
+#[test]
+fn sub_q_string_non_printable() {
+    new_ucmd!()
+        .args(&["non-printable: %q", "\"$test\""])
+        .succeeds()
+        .stdout_only("non-printable: '\"$test\"'");
+}
+
+#[test]
+fn sub_q_string_validate_field_params() {
+    new_ucmd!()
+        .args(&["hello %7q", "world"])
+        .run()
+        .stdout_is("hello ")
+        .stderr_is("printf: %7q: invalid conversion specification\n");
+}
+
+#[test]
+fn sub_q_string_special_non_printable() {
+    new_ucmd!()
+        .args(&["non-printable: %q", "test~"])
+        .succeeds()
+        .stdout_only("non-printable: test~");
+}
+
 #[test]
 fn sub_char() {
     new_ucmd!()