89e785af9
Denys Vlasenko
2018-12-13
Subject
bc: trim config help text, add a few comments, no code changes
Binary
No binary (build failed)
Architecture & Compiler Flags
—
Build Log
(log yok)
Commit Diff GitHub →
miscutils/bc.c+38 -50
| @@ -10,49 +10,34 @@ | |
| //config: bc is a command-line, arbitrary-precision calculator with a | |
| //config: Turing-complete language. See the GNU bc manual | |
| //config: (https://www.gnu.org/software/bc/manual/bc.html) and bc spec | |
| - | //config: (http://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html) |
| - | //config: for details. |
| + | //config: (http://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html). |
| //config: | |
| - | //config: This bc has four differences to the GNU bc: |
| - | //config: |
| - | //config: 1) The period (.) can also be used as a shortcut for "last", as in |
| - | //config: the BSD bc. |
| + | //config: This bc has five differences to the GNU bc: |
| + | //config: 1) The period (.) is a shortcut for "last", as in the BSD bc. |
| //config: 2) Arrays are copied before being passed as arguments to | |
| //config: functions. This behavior is required by the bc spec. | |
| //config: 3) Arrays can be passed to the builtin "length" function to get | |
| - | //config: the number of elements currently in the array. The following |
| - | //config: example prints "1": |
| - | //config: |
| - | //config: a[0] = 0 |
| - | //config: length(a[]) |
| - | //config: |
| + | //config: the number of elements in the array. This prints "1": |
| + | //config: a[0] = 0; length(a[]) |
| //config: 4) The precedence of the boolean "not" operator (!) is equal to | |
| - | //config: that of the unary minus (-), or negation, operator. This still |
| + | //config: that of the unary minus (-) negation operator. This still |
| //config: allows POSIX-compliant scripts to work while somewhat | |
| //config: preserving expected behavior (versus C) and making parsing | |
| //config: easier. | |
| + | //config: 5) "read()" accepts expressions, not only numeric literals. |
| //config: | |
| //config: Options: | |
| - | //config: |
| //config: -i --interactive force interactive mode | |
| + | //config: -q --quiet don't print version and copyright |
| + | //config: -s --standard error if any non-POSIX extensions are used |
| + | //config: -w --warn warn if any non-POSIX extensions are used |
| //config: -l --mathlib use predefined math routines: | |
| - | //config: |
| - | //config: s(expr) = sine of expr in radians |
| - | //config: c(expr) = cosine of expr in radians |
| - | //config: a(expr) = arctangent of expr, returning |
| - | //config: radians |
| - | //config: l(expr) = natural log of expr |
| - | //config: e(expr) = raises e to the power of expr |
| - | //config: j(n, x) = Bessel function of integer order |
| - | //config: n of x |
| - | //config: |
| - | //config: -q --quiet don't print version and copyright. |
| - | //config: -s --standard error if any non-POSIX extensions are used. |
| - | //config: -w --warn warn if any non-POSIX extensions are used. |
| - | //config: -v --version print version and copyright and exit. |
| - | //config: |
| - | //config: Long options are only available if FEATURE_BC_LONG_OPTIONS is |
| - | //config: enabled. |
| + | //config: s(expr) sine in radians |
| + | //config: c(expr) cosine in radians |
| + | //config: a(expr) arctangent, returning radians |
| + | //config: l(expr) natural log |
| + | //config: e(expr) raises e to the power of expr |
| + | //config: j(n, x) Bessel function of integer order n of x |
| //config: | |
| //config:config DC | |
| //config: bool "dc (38 kb; 49 kb when combined with bc)" | |
| @@ -61,33 +46,24 @@ | |
| //config: dc is a reverse-polish notation command-line calculator which | |
| //config: supports unlimited precision arithmetic. See the FreeBSD man page | |
| //config: (https://www.unix.com/man-page/FreeBSD/1/dc/) and GNU dc manual | |
| - | //config: (https://www.gnu.org/software/bc/manual/dc-1.05/html_mono/dc.html) |
| - | //config: for details. |
| + | //config: (https://www.gnu.org/software/bc/manual/dc-1.05/html_mono/dc.html). |
| //config: | |
| //config: This dc has a few differences from the two above: | |
| - | //config: |
| - | //config: 1) When printing a byte stream (command "P"), this bc follows what |
| + | //config: 1) When printing a byte stream (command "P"), this dc follows what |
| //config: the FreeBSD dc does. | |
| - | //config: 2) This dc implements the GNU extensions for divmod ("~") and |
| + | //config: 2) Implements the GNU extensions for divmod ("~") and |
| //config: modular exponentiation ("|"). | |
| - | //config: 3) This dc implements all FreeBSD extensions, except for "J" and |
| - | //config: "M". |
| + | //config: 3) Implements all FreeBSD extensions, except for "J" and "M". |
| //config: 4) Like the FreeBSD dc, this dc supports extended registers. | |
| //config: However, they are implemented differently. When it encounters | |
| //config: whitespace where a register should be, it skips the whitespace. | |
| //config: If the character following is not a lowercase letter, an error | |
| //config: is issued. Otherwise, the register name is parsed by the | |
| //config: following regex: | |
| - | //config: |
| - | //config: [a-z][a-z0-9_]* |
| - | //config: |
| + | //config: [a-z][a-z0-9_]* |
| //config: This generally means that register names will be surrounded by | |
| - | //config: whitespace. |
| - | //config: |
| - | //config: Examples: |
| - | //config: |
| - | //config: l idx s temp L index S temp2 < do_thing |
| - | //config: |
| + | //config: whitespace. Examples: |
| + | //config: l idx s temp L index S temp2 < do_thing |
| //config: Also note that, like the FreeBSD dc, extended registers are not | |
| //config: allowed unless the "-x" option is given. | |
| //config: | |
| @@ -105,11 +81,19 @@ | |
| //config: NOTE: This will require libm to be present for linking. | |
| //config: | |
| //config:config FEATURE_BC_SIGNALS | |
| - | //config: bool "Enable bc/dc signal handling" |
| + | //config: bool "Interactive mode (+4kb)" |
| //config: default y | |
| //config: depends on (BC || DC) && !FEATURE_DC_SMALL | |
| //config: help | |
| - | //config: Enable signal handling for bc and dc. |
| + | //config: Enable interactive mode: when started on a tty, |
| + | //config: ^C interrupts execution and returns to command line, |
| + | //config: errors also return to command line instead of exiting, |
| + | //config: line editing with history is available. |
| + | //config: |
| + | //config: With this option off, input can still be taken from tty, |
| + | //config: but all errors are fatal, ^C is fatal, |
| + | //config: tty is treated exactly the same as any other |
| + | //config: standard input (IOW: no line editing). |
| //config: | |
| //config:config FEATURE_BC_LONG_OPTIONS | |
| //config: bool "Enable bc/dc long options" | |
| @@ -7468,6 +7452,8 @@ static int bc_vm_init(const char *env_len) | |
| bc_program_init(); | |
| bc_parse_create(&G.prs, BC_PROG_MAIN); | |
| + | //TODO: in GNU bc, the check is (isatty(0) && isatty(1)), |
| + | //-i option unconditionally enables this regardless of isatty(): |
| if (isatty(0)) { | |
| #if ENABLE_FEATURE_BC_SIGNALS | |
| G_ttyin = 1; | |
| @@ -7476,10 +7462,12 @@ static int bc_vm_init(const char *env_len) | |
| // In particular, this means ^C won't cause | |
| // stdout to get into "error state" if SIGINT hits | |
| // within write() syscall. | |
| - | // The downside is that ^C while line input is taken |
| + | // |
| + | // The downside is that ^C while tty input is taken |
| // will only be handled after [Enter] since read() | |
| // from stdin is not interrupted by ^C either, | |
| // it restarts, thus fgetc() does not return on ^C. | |
| + | // (This problem manifests only if line editing is disabled) |
| signal_SA_RESTART_empty_mask(SIGINT, record_signo); | |
| // Without SA_RESTART, this exhibits a bug: | |