Branch data     Line data    Source code

       1                 :             : #include "rational.h"
       2                 :             : 
       3                 :             : #include <errno.h>
       4                 :             : #include <stdlib.h>
       5                 :             : #include <string.h>
       6                 :             : #include <unistd.h>
       7                 :             : 
       8                 :             : _Atomic RATIONAL_COLOR_MODE rational_color_mode = COLOR_MODE_AUTO;
       9                 :             : 
      10                 :             : /**
      11                 :             :  * @brief Determine whether terminal colors may be written to a stream
      12                 :             :  *
      13                 :             :  * @details Always mode permits styling for any non-NULL stream, while never
      14                 :             :  *          mode disables it. In automatic mode, the presence of NO_COLOR or
      15                 :             :  *          TERM=dumb disables styling. Otherwise, the decision uses the
      16                 :             :  *          supplied stream's terminal connection at the time of the call,
      17                 :             :  *          including redirections made by a test runner. A terminal connection
      18                 :             :  *          does not establish support for a particular color depth or control
      19                 :             :  *          sequence. The function preserves errno and leaves buffering unchanged
      20                 :             :  *
      21                 :             :  * @param stream Output stream that would receive terminal color sequences;
      22                 :             :  *               NULL disables styling in every mode
      23                 :             :  * @return true when terminal colors may be written, otherwise false
      24                 :             :  */
      25                 :        1390 : bool rational_color_is_enabled(FILE *stream)
      26                 :             : {
      27                 :             :         /* Keep the caller's error code so terminal-detection calls cannot change
      28                 :             :            the error reported by code that runs after this policy check */
      29                 :        1390 :         const int saved_errno = errno;
      30                 :             : 
      31                 :             :         /* Read the shared mode atomically once and use that snapshot throughout
      32                 :             :            this call. Relaxed ordering reads the setting without synchronizing
      33                 :             :            access to unrelated data */
      34                 :        1390 :         const RATIONAL_COLOR_MODE mode = atomic_load_explicit(&rational_color_mode,memory_order_relaxed);
      35                 :             : 
      36                 :             :         /* Start with styling disabled. Never mode and a missing output stream
      37                 :             :            leave this result unchanged because neither enabling branch applies */
      38                 :        1390 :         bool color_is_enabled = false;
      39                 :             : 
      40                 :             :         /* Always mode enables styling for the supplied stream without consulting
      41                 :             :            environment variables or checking whether the stream is a terminal */
      42   [ +  +  +  + ]:        1390 :         if(stream != NULL && COLOR_MODE_ALWAYS == mode)
      43                 :             :         {
      44                 :        1298 :                 color_is_enabled = true;
      45   [ +  +  +  +  :          92 :         } else if(stream != NULL && COLOR_MODE_AUTO == mode && getenv("NO_COLOR") == NULL){
                   +  + ]
      46                 :             :                 /* Automatic detection runs only when NO_COLOR is absent. Its presence
      47                 :             :                    disables automatic styling even when its value is an empty string */
      48                 :          39 :                 const char *term = getenv("TERM");
      49                 :             : 
      50                 :             :                 /* The exact TERM value dumb disables automatic styling. An unset TERM
      51                 :             :                    or any other value allows the stream's terminal check to proceed */
      52   [ +  +  +  + ]:          39 :                 if(term == NULL || 0 != strcmp(term,"dumb"))
      53                 :             :                 {
      54                 :             :                         /* Resolve the descriptor of this specific stream on each check.
      55                 :             :                            This detects its current redirection and lets stdout and stderr
      56                 :             :                            receive independent decisions */
      57                 :          33 :                         const int stream_descriptor = fileno(stream);
      58                 :             : 
      59                 :             :                         /* Require a valid descriptor connected to a terminal or
      60                 :             :                            pseudoterminal. Files, pipes, and failed checks leave styling
      61                 :             :                            disabled. This tests the connection, not terminal capabilities */
      62   [ +  -  +  + ]:          33 :                         if(stream_descriptor >= 0 && isatty(stream_descriptor) == 1)
      63                 :             :                         {
      64                 :           4 :                                 color_is_enabled = true;
      65                 :             :                         }
      66                 :             :                 }
      67                 :             :         }
      68                 :             : 
      69                 :             :         /* Restore the caller's error code and return the decision. The caller
      70                 :             :            uses it to select styled or plain text for this output stream */
      71                 :        1390 :         errno = saved_errno;
      72                 :        1390 :         return(color_is_enabled);
      73                 :             : }