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214 lines
4.7 KiB
214 lines
4.7 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* |
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* Misc librarized functions for cmdline poking. |
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*/ |
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#include <linux/kernel.h> |
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#include <linux/string.h> |
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#include <linux/ctype.h> |
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#include <asm/setup.h> |
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static inline int myisspace(u8 c) |
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{ |
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return c <= ' '; /* Close enough approximation */ |
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} |
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/** |
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* Find a boolean option (like quiet,noapic,nosmp....) |
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* |
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* @cmdline: the cmdline string |
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* @option: option string to look for |
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* |
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* Returns the position of that @option (starts counting with 1) |
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* or 0 on not found. @option will only be found if it is found |
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* as an entire word in @cmdline. For instance, if @option="car" |
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* then a cmdline which contains "cart" will not match. |
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*/ |
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static int |
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__cmdline_find_option_bool(const char *cmdline, int max_cmdline_size, |
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const char *option) |
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{ |
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char c; |
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int pos = 0, wstart = 0; |
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const char *opptr = NULL; |
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enum { |
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st_wordstart = 0, /* Start of word/after whitespace */ |
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st_wordcmp, /* Comparing this word */ |
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st_wordskip, /* Miscompare, skip */ |
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} state = st_wordstart; |
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if (!cmdline) |
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return -1; /* No command line */ |
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/* |
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* This 'pos' check ensures we do not overrun |
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* a non-NULL-terminated 'cmdline' |
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*/ |
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while (pos < max_cmdline_size) { |
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c = *(char *)cmdline++; |
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pos++; |
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switch (state) { |
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case st_wordstart: |
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if (!c) |
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return 0; |
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else if (myisspace(c)) |
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break; |
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state = st_wordcmp; |
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opptr = option; |
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wstart = pos; |
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fallthrough; |
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case st_wordcmp: |
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if (!*opptr) { |
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/* |
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* We matched all the way to the end of the |
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* option we were looking for. If the |
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* command-line has a space _or_ ends, then |
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* we matched! |
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*/ |
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if (!c || myisspace(c)) |
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return wstart; |
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/* |
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* We hit the end of the option, but _not_ |
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* the end of a word on the cmdline. Not |
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* a match. |
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*/ |
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} else if (!c) { |
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/* |
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* Hit the NULL terminator on the end of |
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* cmdline. |
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*/ |
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return 0; |
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} else if (c == *opptr++) { |
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/* |
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* We are currently matching, so continue |
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* to the next character on the cmdline. |
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*/ |
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break; |
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} |
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state = st_wordskip; |
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fallthrough; |
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case st_wordskip: |
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if (!c) |
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return 0; |
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else if (myisspace(c)) |
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state = st_wordstart; |
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break; |
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} |
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} |
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return 0; /* Buffer overrun */ |
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} |
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/* |
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* Find a non-boolean option (i.e. option=argument). In accordance with |
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* standard Linux practice, if this option is repeated, this returns the |
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* last instance on the command line. |
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* |
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* @cmdline: the cmdline string |
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* @max_cmdline_size: the maximum size of cmdline |
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* @option: option string to look for |
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* @buffer: memory buffer to return the option argument |
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* @bufsize: size of the supplied memory buffer |
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* |
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* Returns the length of the argument (regardless of if it was |
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* truncated to fit in the buffer), or -1 on not found. |
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*/ |
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static int |
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__cmdline_find_option(const char *cmdline, int max_cmdline_size, |
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const char *option, char *buffer, int bufsize) |
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{ |
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char c; |
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int pos = 0, len = -1; |
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const char *opptr = NULL; |
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char *bufptr = buffer; |
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enum { |
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st_wordstart = 0, /* Start of word/after whitespace */ |
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st_wordcmp, /* Comparing this word */ |
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st_wordskip, /* Miscompare, skip */ |
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st_bufcpy, /* Copying this to buffer */ |
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} state = st_wordstart; |
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if (!cmdline) |
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return -1; /* No command line */ |
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/* |
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* This 'pos' check ensures we do not overrun |
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* a non-NULL-terminated 'cmdline' |
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*/ |
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while (pos++ < max_cmdline_size) { |
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c = *(char *)cmdline++; |
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if (!c) |
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break; |
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switch (state) { |
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case st_wordstart: |
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if (myisspace(c)) |
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break; |
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state = st_wordcmp; |
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opptr = option; |
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fallthrough; |
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case st_wordcmp: |
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if ((c == '=') && !*opptr) { |
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/* |
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* We matched all the way to the end of the |
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* option we were looking for, prepare to |
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* copy the argument. |
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*/ |
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len = 0; |
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bufptr = buffer; |
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state = st_bufcpy; |
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break; |
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} else if (c == *opptr++) { |
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/* |
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* We are currently matching, so continue |
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* to the next character on the cmdline. |
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*/ |
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break; |
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} |
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state = st_wordskip; |
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fallthrough; |
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case st_wordskip: |
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if (myisspace(c)) |
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state = st_wordstart; |
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break; |
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case st_bufcpy: |
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if (myisspace(c)) { |
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state = st_wordstart; |
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} else { |
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/* |
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* Increment len, but don't overrun the |
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* supplied buffer and leave room for the |
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* NULL terminator. |
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*/ |
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if (++len < bufsize) |
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*bufptr++ = c; |
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} |
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break; |
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} |
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} |
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if (bufsize) |
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*bufptr = '\0'; |
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return len; |
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} |
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int cmdline_find_option_bool(const char *cmdline, const char *option) |
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{ |
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return __cmdline_find_option_bool(cmdline, COMMAND_LINE_SIZE, option); |
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} |
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int cmdline_find_option(const char *cmdline, const char *option, char *buffer, |
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int bufsize) |
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{ |
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return __cmdline_find_option(cmdline, COMMAND_LINE_SIZE, option, |
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buffer, bufsize); |
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}
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