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| -rw-r--r-- | package/pkg-utils.mk | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/package/pkg-utils.mk b/package/pkg-utils.mk index f88313ab53..c61b3b67c4 100644 --- a/package/pkg-utils.mk +++ b/package/pkg-utils.mk @@ -104,6 +104,43 @@ define sep endef +PERCENT = % +QUOTE = ' +# ' # Meh... syntax-highlighting + +# This macro properly escapes a command string, then prints it with printf: +# +# - first, backslash '\' are self-escaped, so that they do not escape +# the following char and so that printf properly outputs a backslash; +# +# - next, single quotes are escaped by closing an existing one, adding +# an escaped one, and re-openning a new one (see below for the reason); +# +# - then '%' signs are self-escaped so that the printf does not interpret +# them as a format specifier, in case the variable contains an actual +# printf with a format; +# +# - finally, $(sep) is replaced with the literal '\n' so that make does +# not break on the so-expanded variable, but so that the printf does +# correctly output an LF. +# +# Note: this must be escaped in this order to avoid over-escaping the +# previously escaped elements. +# +# Once everything has been escaped, it is passed between single quotes +# (that's why the single-quotes are escaped they way they are, above, +# and why the dollar sign is not escaped) to printf(1). A trailing +# newline is apended, too. +# +# Note: leading or trailing spaces are *not* stripped. +# +define PRINTF + printf '$(subst $(sep),\n,\ + $(subst $(PERCENT),$(PERCENT)$(PERCENT),\ + $(subst $(QUOTE),$(QUOTE)\$(QUOTE)$(QUOTE),\ + $(subst \,\\,$(1)))))\n' +endef + # check-deprecated-variable -- throw an error on deprecated variables # example: # $(eval $(call check-deprecated-variable,FOO_MAKE_OPT,FOO_MAKE_OPTS)) |
