- Conditional execution (`&&`, `||`)
- File redirection (`<file`, `2>&1`, etc.)
- Globbing (`*`, `?`, `[...]`)
-- Quoting with escape sequences (`"\r...\n"`)
-- Environment variables (`set`, `unset`, `$VAR$`, etc.)
+- Quoting (`'...', "..."`)
+- Variables (`set`, `unset`, `$VAR$`, etc.)
- Aliasing (`alias`, `unalias`)
- Configuration files (`~.thuslogin`, `~.thusrc`)
- Cached history (`~.thushistory`)
### Quotes
-Quoting is done with double quotes (`"..."`) and undergoes no shell
-substitution, similar to single quotes in Bourne shell. In place of
-substitution, quotes can be concatenated with surrounding tokens not separated
-by whitespace.
+Like most other shells, variables, tildes, and escape sequences will be expanded
+inside of double quotes, but not single quotes. *Unlike* other shells however,
+quotes do not concatenate with other arguments that are not separated from the
+quote by whitespace. For example, the command `echo "abc"def` would print
+`abc def` whereas other shells would combine them into a single argument and
+print `abcdef`.
-### Environment variables and aliases
+### Variables and aliases
-Environment variables are referred to by tokens that begin and end with a `$`.
-For example, evaluating the path would look like `$PATH$`. Setting environment
+Variables are referred to by strings of characters that begin and end with a
+`$`. For example, evaluating the path variable would look like `$PATH$`. Setting
variables is done with the `set` built-in command, not with the `name=value`
syntax. This syntax is similarly avoided when declaring aliases with the `alias`
built-in command.
+Additionally, all shell variables are automatically made to be environment
+variables, so there's no need to `export` variables.
+
### Leading and trailing slashes
Prepending `./` to executables located in the current directory is not mandatory
unless there already exists an executable in `$PATH$` with the same name that
you would like to override.
-The `$HOME$`, `$PWD$`, and `$PATH$` environment variables are always initialized
-with trailing slashes. Therefore, whenever one of these variables or `~` is
+The `$HOME$`, `$PWD$`, and `$PATH$` variables are always initialized with
+trailing slashes. Therefore, whenever one of these variables or `~` is
substituted in the shell, it will retain the trailing slash.
### File redirection
-For the sake of syntactic consistency, there is no whitespace between a file
-redirection operator and the filename that comes after it.
+If there is whitespace between a file redirection operator and a filename
+following it, then it is *not* parsed as a file redirection, but instead as two
+separate arguments. Something like `ls >file` would redirect the output of the
+`ls` command to `file`, whereas `ls > file` would list any files named `>` and
+`file`.
## Resources
#include "utils.h"
int parse(struct context *c) {
- int globbing, e, offset, globflags;
+ int globbing, quote, v, offset, globflags;
size_t prevsublen, sublen;
- char *stlend, *p, *end, *env, term, **sub;
+ char *stlend, *p, *end, *var, term, **sub;
long l;
static glob_t globs;
c->r->mode = NONE;
c->prev = c->current;
+ for (end = c->b; *end; ++end);
+ prevsublen = globbing = quote = 0;
+ sub = NULL;
if (globs.gl_pathc) {
globfree(&globs);
globs.gl_pathc = 0;
}
- prevsublen = globbing = 0;
for (*c->t = c->b; *c->b; ++c->b) switch (*c->b) {
case '<':
case '>':
- if (c->r->mode) {
- note("Invalid syntax for file redirection");
- return quit(c);
- }
- if (c->r - c->redirects == MAXREDIRECTS) {
- note("Too many file redirects, exceeds %d redirect limit", MAXREDIRECTS);
- return quit(c);
- }
- if (*c->t != c->b) {
- if ((l = strtol(*c->t, &stlend, 10)) < 0 || l > INT_MAX || stlend != c->b) {
- note("Invalid value for a file redirection");
- return quit(c);
- }
- c->r->newfd = l;
- } else c->r->newfd = *c->b == '>';
+ if (quote || c->r->mode) break;
+
+ if (*c->t == c->b) c->r->newfd = *c->b == '>';
+ else if ((c->r->newfd = strtol(*c->t, &stlend, 10)) < 0
+ || c->r->newfd > INT_MAX || stlend != c->b)
+ break;
c->r->mode = *c->b;
if (*(c->b + 1) == '>') {
++c->r->mode;
}
c->r->oldname = c->b + 1;
if (*(c->b + 1) == '&') ++c->b;
+
break;
case '$':
p = c->b++;
while (*c->b && *c->b != '$') ++c->b;
if (!*c->b) {
- note("Environment variable lacks a terminating `$'");
+ note("Variable left open-ended");
return quit(c);
}
*c->b++ = '\0';
- for (end = c->b; *end; ++end);
l = strtol(p + 1, &stlend, 10);
errno = 0;
- if (stlend == c->b - 1) env = l >= 0 && l < argcount ? arglist[l] : c->b - 1;
+ if (stlend == c->b - 1) var = l >= 0 && l < argcount ? arglist[l] : c->b - 1;
else if (strcmp(p + 1, "^") == 0) {
- if (!sprintf(env = (char [12]){0}, "%d", status)) {
+ if (!sprintf(var = (char [12]){0}, "%d", status)) {
note("Unable to get previous command status");
return quit(c);
}
- } else if (!(env = getenv(p + 1))) {
- note("Environment variable does not exist");
- return quit(c);
- }
+ } else if (!(var = getenv(p + 1))) var = "";
- e = strlen(env);
- offset = e - (c->b - p);
+ v = strlen(var);
+ offset = v - (c->b - p);
memmove(c->b + offset, c->b, end - c->b + 1);
- strncpy(p, env, e);
+ strncpy(p, var, v);
c->b += offset - 1;
+ end += offset;
break;
case '~':
- for (end = c->b; *end; ++end);
offset = strlen(home);
memmove(c->b + offset, c->b + 1, end - c->b);
strncpy(c->b, home, offset);
c->b += offset - 1;
+ end += offset;
break;
- case '[':
- while (*c->b && *c->b != ']') ++c->b;
+ case '\'':
+ if (quote) break;
+
+ *c->b = '\0';
+ if (*c->t != c->b) ++c->t;
+ *c->t = ++c->b;
+
+ while (*c->b && *c->b != '\'') ++c->b;
if (!*c->b) {
- note("Range in glob left open-ended");
+ note("Quote left open-ended");
return quit(c);
}
- case '*':
- case '?':
- globbing = 1;
+
+ *c->b = '\0';
+ ++c->t;
+ *c->t = c->b + 1;
+
break;
case '"':
- for (end = (p = c->b) + 1, c->b = NULL; *end; ++end) if (!c->b) {
- if (*end == '"') c->b = end;
- if (*end == '\\') ++end;
- }
- if (!c->b) {
- note("Quote left open-ended");
- return quit(c);
+ *c->b = '\0';
+ if (quote || *c->t != c->b) ++c->t;
+ *c->t = c->b + 1;
+
+ quote = !quote;
+
+ break;
+ case '\\':
+ if (!quote) break;
+ switch (*(c->b + 1)) {
+ case '$':
+ case '"':
+ case '\\':
+ break;
+ default:
+ memmove(c->b, c->b + 1, end-- - c->b--);
+ *(c->b + 1) = *c->b;
}
- memmove(p, p + 1, end-- - p);
- --c->b;
+ memmove(c->b, c->b + 1, end-- - c->b);
+ break;
+ case '*':
+ case '?':
+ case '[':
+ if (quote) break;
- while (p != c->b) if (*p++ == '\\') {
- switch (*p) {
- case 't':
- *p = '\t';
- break;
- case 'v':
- *p = '\v';
- break;
- case 'r':
- *p = '\r';
- break;
- case 'n':
- *p = '\n';
- break;
- }
- memmove(p - 1, p, end-- - p + 1);
- --c->b;
+ if (*c->b == '[') {
+ p = c->b;
+ while (*p && *p != ' ' && *p != ']') ++p;
+ if (*p != ']') break;
+ c->b = p;
}
- memmove(p, p + 1, end-- - p);
- --c->b;
+ globbing = 1;
break;
case '#':
- *(c->b + 1) = '\0';
case '&':
case '|':
case ';':
case ' ':
+ if (quote) break;
+ if (*c->b == '#') *(c->b + 1) = '\0';
+
term = *c->b;
*c->b = '\0';
- if (c->r->mode) {
- switch (*c->r->oldname) {
- case '&':
- if ((l = strtol(++c->r->oldname, &stlend, 10)) < 0 || l > INT_MAX
- || *stlend) {
- case '\0':
- note("Invalid syntax for file redirection");
- return quit(c);
- }
+ if (c->r->mode) switch (*c->r->oldname) {
+ case '&':
+ ++c->r->oldname;
+ if (*c->r->oldname && (l = strtol(c->r->oldname, &stlend, 10)) >= 0
+ && l <= INT_MAX && !*stlend) {
c->r->oldfd = l;
c->r->oldname = NULL;
+ default:
+ if (c->r - c->redirects == MAXREDIRECTS) {
+ note("Too many file redirects, exceeds %d redirect limit", MAXREDIRECTS);
+ return quit(c);
+ }
+ ++c->r;
+ *c->t = c->b;
}
- (++c->r)->mode = NONE;
- globbing = 0;
+ case '\0':
+ c->r->mode = NONE;
+ }
- *c->t = c->b;
- } else if (!c->alias && c->t == c->tokens && (sub = getalias(c->tokens[0]))
- || globbing) {
- if (globbing) {
+ if (*c->t != c->b) {
+ if (!c->alias && c->t == c->tokens && (sub = getalias(c->tokens[0])))
+ for (sublen = 0; sub[sublen]; ++sublen);
+ else if (globbing) {
globflags = GLOB_MARK;
if (prevsublen) globflags |= GLOB_APPEND;
switch (glob(*c->t, globflags, NULL, &globs)) {
sub = globs.gl_pathv + prevsublen;
prevsublen = globs.gl_pathc;
globbing = 0;
- } else for (sublen = 0; sub[sublen]; ++sublen);
-
- memcpy(c->t, sub, sublen * sizeof*c->t);
- c->t += sublen;
- *c->t = c->b;
- } else if (*c->t != c->b) ++c->t;
+ }
+ if (sub) {
+ memcpy(c->t, sub, sublen * sizeof*c->t);
+ c->t += sublen - 1;
+ sub = NULL;
+ }
+ ++c->t;
+ }
if (term != ' ') {
if (c->t != c->tokens) {
return 1;
}
+
*c->t = c->b + 1;
}
+ if (quote) {
+ note("Quote left open-ended");
+ return quit(c);
+ }
+
switch (c->current.term) {
case AND:
case PIPE:
}
void init(void) {
- char buffer[PATH_MAX], *shlvlstr;
+ char *shlvlstr, buffer[PATH_MAX];
size_t l;
long shlvl;
note("Unable to update $SHLVL$ environment variable");
if (!(home = getenv("HOME"))) fatal("Unable to find home directory");
- if (shlvl == 1) {
- l = strlen(home);
- if (home[l - 1] != '/') {
- strcpy(buffer, home);
- buffer[l] = '/';
- buffer[l + 1] = '\0';
- if (setenv("HOME", buffer, 1) == -1 || !(home = getenv("HOME")))
- fatal("Unable to append trailing slash to $HOME$");
- }
-
- if (!getcwd(buffer, PATH_MAX)) fatal("Unable to find current directory");
- l = strlen(buffer);
+ l = strlen(home);
+ if (home[l - 1] != '/') {
+ strcpy(buffer, home);
buffer[l] = '/';
buffer[l + 1] = '\0';
- if (setenv("PWD", buffer, 1) == -1)
- fatal("Unable to append trailing slash to $PWD$");
-
- if (setenv("PATH", "/usr/local/bin/:/usr/local/sbin/"
- ":/usr/bin/:/usr/sbin/:/bin/:/sbin/", 1) == -1)
- fatal("Unable to initialize $PATH$");
+ if (setenv("HOME", buffer, 1) == -1 || !(home = getenv("HOME")))
+ note("Unable to append trailing slash to $HOME$");
}
+ if (!getcwd(buffer, PATH_MAX)) fatal("Unable to find current directory");
+ l = strlen(buffer);
+ buffer[l] = '/';
+ buffer[l + 1] = '\0';
+ if (setenv("PWD", buffer, 1) == -1)
+ note("Unable to append trailing slash to $PWD$");
+
+ if (shlvl == 1
+ && setenv("PATH", "/usr/local/bin/:/usr/local/sbin/:"
+ "/usr/bin/:/usr/sbin/:/bin/:/sbin/", 1) == -1)
+ note("Unable to initialize $PATH$");
+
initfg();
initbg();
inithistory();
code / thus.git / commitdiff