# systemd service unit file for EdenFS.
# systemd: https://freedesktop.org/wiki/Software/systemd/
# EdenFS: https://our.intern.facebook.com/intern/wiki/Eden/

[Unit]
Description=EdenFS FUSE filesystem

[Service]
Environment=EDENFS_EXECUTABLE_PATH=/usr/local/bin/edenfs
Environment=EDENFS_EXTRA_ARGUMENTS=
Environment=EDENFS_SYSTEM_CONFIG_DIR=/etc/eden
Environment=EDENFS_USER_CONFIG_DIR=%h/.edenrc

EnvironmentFile=-%f/systemd.conf

Environment=EDENFS_CONFIG_DIR=%f
Environment=EDENFS_STARTUP_LOG=%f/startup.log
Environment=EDENFS_USER_ID=%U

# Some important escaping rules for how the quoted argument of 'sh -c' within
# ExecStart is interpreted by systemd:
#
# * '\' followed by a newline is replaced with ' ' (a space). (You *must* escape
#    newlines with '\'.) A leading '\' escapes '\'. [1]
# * '\' followed by "'" (a single quote) is replaced with single quote. [2]
# * '$' followed by '$' is replaced with a single '$'. [3]
# * '%' followed by '%' is replaced with a single '%'. [4]
#
# Recommendations:
#
# * End each physical line with ' \' (a space followed by a backslash). [1]
# * Escape "'" (a single quote) using '\'. Use "can\'t", not "can't". Prefer
#   using double quotes instead of single quotes. [2]
# * Escape '$' using '$'. Use '$${var}', not '$var' or '${var}'. [3]
# * Escape '%' using '%'. Use '100%% cool', not '100% cool'. [4]
# * Terminate commands with ';', if appropriate, instead of a newline. [5]
#
# References:
#
# [1] https://www.freedesktop.org/software/systemd/man/systemd.syntax.html
#     https://github.com/systemd/systemd/blob/66a5b5ce9b991327d594f7b635de16999ca54093/src/shared/conf-parser.c#L354-L365
#
# [2] https://github.com/systemd/systemd/blob/66a5b5ce9b991327d594f7b635de16999ca54093/src/basic/extract-word.c#L68
#     https://github.com/systemd/systemd/blob/66a5b5ce9b991327d594f7b635de16999ca54093/src/basic/escape.c#L48-L51
#
# [3] https://github.com/systemd/systemd/blob/66a5b5ce9b991327d594f7b635de16999ca54093/src/basic/env-util.c#L526-L542
#
# [4] https://github.com/systemd/systemd/blob/66a5b5ce9b991327d594f7b635de16999ca54093/src/core/unit-printf.c#L217
#     https://github.com/systemd/systemd/blob/66a5b5ce9b991327d594f7b635de16999ca54093/src/shared/specifier.c#L48-L49
#
# [5] https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html

ExecStart=/bin/sh -c ' \
    set -e; \
    set -u; \
    \
    newline="$$(printf "\\nx")"; \
    newline="$${newline::-1}"; \
    \
    `# Split EDENFS_EXTRA_ARGUMENTS on newlines, not whitespace.`; \
    IFS="$${newline}"; \
    \
    exec_edenfs_as_root() { \
        if [ "$${EDENFS_USER_ID}" -eq 0 ]; then \
            exec "$${EDENFS_EXECUTABLE_PATH}" --allowRoot "$${@}"; \
        else \
            exec /usr/bin/sudo -- "$${EDENFS_EXECUTABLE_PATH}" "$${@}"; \
        fi; \
    }; \
    \
    exec_edenfs_as_root \
        --configPath "$${EDENFS_USER_CONFIG_DIR}" \
        --edenDir "$${EDENFS_CONFIG_DIR}" \
        --edenfs \
        --etcEdenDir "$${EDENFS_SYSTEM_CONFIG_DIR}" \
        --experimentalSystemd \
        --foreground \
        --startupLogPath "$${EDENFS_STARTUP_LOG}" \
        $${EDENFS_EXTRA_ARGUMENTS}; \
'

NotifyAccess=all
Type=notify

NoNewPrivileges=false

[Install]